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2. The Dilworth theorems: Selected papers of Robert P. Dilworth
- Author
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M.K Bennett
- Subjects
Combinatorics ,Mathematics(all) ,General Mathematics ,Mathematics - Published
- 1992
3. Hill representations for ∗-linear matrix maps
- Author
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A. van der Merwe and S. ter Horst
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Combinatorics ,Linear map ,Matrix (mathematics) ,General Mathematics ,Nonnegative matrix ,Linear matrix ,Hermitian matrix ,Mathematics - Abstract
In the paper (Hill, 1973) from 1973 R.D. Hill studied linear matrix maps L : ℂ q × q → ℂ n × n which map Hermitian matrices to Hermitian matrices, or equivalently, preserve adjoints, i.e., L ( V ∗ ) = L ( V ) ∗ , via representations of the form L ( V ) = ∑ k , l = 1 m H k l A l V A k ∗ , V ∈ ℂ q × q , for matrices A 1 , … , A m ∈ ℂ n × q and continued his study of such representations in later work, sometimes with co-authors, to completely positive matrix maps and associated matrix reorderings. In this paper we expand the study of such representations, referred to as Hill representations here, in various directions. In particular, we describe which matrices A 1 , … , A m can appear in Hill representations (provided the number m is minimal) and determine the associated Hill matrix H = H k l explicitly. Also, we describe how different Hill representations of L (again with m minimal) are related and investigate further the implication of ∗ -linearity on the linear map L .
- Published
- 2022
4. On additive and multiplicative decompositions of sets of integers with restricted prime factors, I. (Smooth numbers)
- Author
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Kálmán Győry, Lajos Hajdu, and András Sárközy
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Sequence ,Conjecture ,Mathematics - Number Theory ,General Mathematics ,Sieve (category theory) ,010102 general mathematics ,Multiplicative function ,010103 numerical & computational mathematics ,01 natural sciences ,Combinatorics ,Prime factor ,FOS: Mathematics ,Number Theory (math.NT) ,0101 mathematics ,Unit (ring theory) ,Mathematics - Abstract
In Sarkozy (2001) the third author of this paper presented two conjectures on the additive decomposability of the sequence of ”smooth” (or ”friable”) numbers. Elsholtz and Harper (2015) proved (by using sieve methods) the second (less demanding) conjecture. The goal of this paper is to extend and sharpen their result in three directions by using a different approach (based on the theory of S -unit equations).
- Published
- 2021
5. On some universal Morse–Sard type theorems
- Author
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Alba Roviello, Adele Ferone, Mikhail V. Korobkov, Ferone, A., Korobkov, M. V., and Roviello, A.
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Uncertainty principle ,Dubovitskii-Federer theorems ,Near critical ,Morse-Sard theorem ,Applied Mathematics ,General Mathematics ,010102 general mathematics ,Algebraic geometry ,Morse code ,Sobolev-Lorentz mapping ,Holder mapping ,01 natural sciences ,law.invention ,Sobolev space ,Combinatorics ,law ,0103 physical sciences ,010307 mathematical physics ,Differentiable function ,Bessel potential space ,0101 mathematics ,Critical set ,Mathematics - Abstract
The classical Morse–Sard theorem claims that for a mapping v : R n → R m + 1 of class C k the measure of critical values v ( Z v , m ) is zero under condition k ≥ n − m . Here the critical set, or m-critical set is defined as Z v , m = { x ∈ R n : rank ∇ v ( x ) ≤ m } . Further Dubovitskiĭ in 1957 and independently Federer and Dubovitskiĭ in 1967 found some elegant extensions of this theorem to the case of other (e.g., lower) smoothness assumptions. They also established the sharpness of their results within the C k category. Here we formulate and prove a bridge theorem that includes all the above results as particular cases: namely, if a function v : R n → R d belongs to the Holder class C k , α , 0 ≤ α ≤ 1 , then for every q > m the identity H μ ( Z v , m ∩ v − 1 ( y ) ) = 0 holds for H q -almost all y ∈ R d , where μ = n − m − ( k + α ) ( q − m ) . Intuitively, the sense of this bridge theorem is very close to Heisenberg's uncertainty principle in theoretical physics: the more precise is the information we receive on measure of the image of the critical set, the less precisely the preimages are described, and vice versa. The result is new even for the classical C k -case (when α = 0 ); similar result is established for the Sobolev classes of mappings W p k ( R n , R d ) with minimal integrability assumptions p = max ( 1 , n / k ) , i.e., it guarantees in general only the continuity (not everywhere differentiability) of a mapping. However, using some N-properties for Sobolev mappings, established in our previous paper, we obtained that the sets of nondifferentiability points of Sobolev mappings are fortunately negligible in the above bridge theorem. We cover also the case of fractional Sobolev spaces. The proofs of the most results are based on our previous joint papers with J. Bourgain and J. Kristensen (2013, 2015). We also crucially use very deep Y. Yomdin's entropy estimates of near critical values for polynomials (based on algebraic geometry tools).
- Published
- 2020
6. Reproducing kernel orthogonal polynomials on the multinomial distribution
- Author
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Robert C. Griffiths and Persi Diaconis
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Numerical Analysis ,Stationary distribution ,Markov chain ,Applied Mathematics ,General Mathematics ,010102 general mathematics ,Poisson kernel ,010103 numerical & computational mathematics ,Kravchuk polynomials ,01 natural sciences ,Combinatorics ,symbols.namesake ,Kernel (statistics) ,Orthogonal polynomials ,symbols ,Test statistic ,Multinomial distribution ,0101 mathematics ,Analysis ,Mathematics - Abstract
Diaconis and Griffiths (2014) study the multivariate Krawtchouk polynomials orthogonal on the multinomial distribution. In this paper we derive the reproducing kernel orthogonal polynomials Q n ( x , y ; N , p ) on the multinomial distribution which are sums of products of orthonormal polynomials in x and y of fixed total degree n = 0 , 1 , … , N . The Poisson kernel ∑ n = 0 N ρ n Q n ( x , y ; N , p ) arises naturally from a probabilistic argument. An application to a multinomial goodness of fit test is developed, where the chi-squared test statistic is decomposed into orthogonal components which test the order of fit. A new duplication formula for the reproducing kernel polynomials in terms of the 1-dimensional Krawtchouk polynomials is derived. The duplication formula allows a Lancaster characterization of all reversible Markov chains with a multinomial stationary distribution whose eigenvectors are multivariate Krawtchouk polynomials and where eigenvalues are repeated within the same total degree. The χ 2 cutoff time, and total variation cutoff time is investigated in such chains. Emphasis throughout the paper is on a probabilistic understanding of the polynomials and their applications, particularly to Markov chains.
- Published
- 2019
7. Comparison of probabilistic and deterministic point sets on the sphere
- Author
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Peter J. Grabner and T. A. Stepanyuk
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Unit sphere ,Numerical Analysis ,Sequence ,Applied Mathematics ,General Mathematics ,Existential quantification ,010102 general mathematics ,Probabilistic logic ,Sampling (statistics) ,010103 numerical & computational mathematics ,01 natural sciences ,Combinatorics ,Point (geometry) ,0101 mathematics ,Constant (mathematics) ,Analysis ,Mathematics - Abstract
In this paper we make a comparison between certain probabilistic and deterministic point sets and show that some deterministic constructions (especially spherical t -designs) are better or as good as probabilistic ones like the jittered sampling model. We find asymptotic equalities for the discrete Riesz s -energy of sequences of well separated t -designs on the unit sphere S d ⊂ R d + 1 , d ≥ 2 . The case d = 2 was studied in Hesse (2009) and Hesse and Leopardi (2008). In Bondarenko et al., (2015) it was established that for d ≥ 2 , there exists a constant c d , such that for every N > c d t d there exists a well-separated spherical t -design on S d with N points. This paper gives results, based on recent developments that there exists a sequence of well separated spherical t -designs such that t and N are related by N ≍ t d .
- Published
- 2019
8. On the existence of optimal meshes in every convex domain on the plane
- Author
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András Kroó
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Numerical Analysis ,Polynomial ,Conjecture ,Degree (graph theory) ,Plane (geometry) ,Applied Mathematics ,General Mathematics ,010102 general mathematics ,Polytope ,010103 numerical & computational mathematics ,01 natural sciences ,Combinatorics ,Cardinality ,Polygon mesh ,0101 mathematics ,Constant (mathematics) ,Analysis ,Mathematics - Abstract
In this paper we study the so called optimal polynomial meshes for domains in K ⊂ R d , d ≥ 2 . These meshes are discrete point sets Y n of cardinality c n d which have the property that ‖ p ‖ K ≤ A ‖ p ‖ Y n for every polynomial p of degree at most n with a constant A > 1 independent of n . It was conjectured earlier that optimal polynomial meshes exist in every convex domain. This statement was previously shown to hold for polytopes and C 2 like domains. In this paper we give a complete affirmative answer to the above conjecture when d = 2 .
- Published
- 2019
9. K-Narayana sequence self-Similarity. flip graph views of k-Narayana self-Similarity
- Author
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James F. Peters, Bahar Kuloǧlu, and Engin Özkan
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Sequence ,Spanning subgraph ,Self-similarity ,General Mathematics ,Applied Mathematics ,General Physics and Astronomy ,Statistical and Nonlinear Physics ,Pascal (programming language) ,Graph ,Combinatorics ,Free group ,computer ,Mathematics ,computer.programming_language - Abstract
This paper introduces self-similarity inherent in planar Milich-Jennings centered flip graphs derived from the Narayana sequence. We show that self-similarity found in a Narayana sequence yields a connected spanning subgraph with a centered flip. This paper has several main results (1) Every Narayana sequence constructs a flip graph, (2) Every Narayana sequence is self-similar and (3) Every Pascal 3-triangle has a free group presentation.
- Published
- 2021
10. Generating new ideals using weighted density via modulus functions
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Adam Kwela, Pratulananda Das, and Kumardipta Bose
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Combinatorics ,Modulo operation ,General Mathematics ,010102 general mathematics ,Modulus ,010103 numerical & computational mathematics ,0101 mathematics ,01 natural sciences ,Mathematics - Abstract
In this paper we extend the idea of weighted density of Balcerzak et al. (2015) by using a modulus function and introduce the idea f -density of weight g of subsets of ω ≔ { 0 , 1 , … } (at the same time extending the notion of f -density (Aizpuru et al., 2014)), which we name d g f where g : ω → [ 0 , ∞ ) satisfies g ( n ) → ∞ and n ∕ g ( n ) ↛ 0 and f is a modulus function. The aim of this paper is to show that we can get new ideals Z g ( f ) consisting of sets A ⊂ ω for which d g f ( A ) = 0 different from all the previously constructed ideals Z g of Balcerzak et al. (2015) and moreover they retain all the nice properties of the ideals Z g .
- Published
- 2018
11. Decomposition spaces, incidence algebras and Möbius inversion III: The decomposition space of Möbius intervals
- Author
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Joachim Kock, Imma Gálvez-Carrillo, Andrew Tonks, Universitat Politècnica de Catalunya. Departament de Matemàtiques, and Universitat Politècnica de Catalunya. GEOMVAP - Geometria de Varietats i Aplicacions
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Pure mathematics ,Mathematics::General Mathematics ,Mathematics::Number Theory ,General Mathematics ,Coalgebra ,18 Category theory [Classificació AMS] ,Structure (category theory) ,18G Homological algebra [homological algebra] ,Combinatorial topology ,55 Algebraic topology::55P Homotopy theory [Classificació AMS] ,Algebraic topology ,Space (mathematics) ,2-Segal space ,01 natural sciences ,Combinatorics ,decomposition space ,18G30, 16T10, 06A11, 18-XX, 55Pxx ,Mathematics::Category Theory ,0103 physical sciences ,Mathematics - Combinatorics ,Mathematics::Metric Geometry ,Matemàtiques i estadística::Topologia::Topologia algebraica [Àrees temàtiques de la UPC] ,Mathematics - Algebraic Topology ,0101 mathematics ,06 Order, lattices, ordered algebraic structures::06A Ordered sets [Classificació AMS] ,Mathematics ,Topologia combinatòria ,CULF functor ,Mathematics::Combinatorics ,Functor ,Mathematics::Complex Variables ,Homotopy ,010102 general mathematics ,Mathematics - Category Theory ,Möbius interval ,Topologia algebraica ,Hopf algebra ,18 Category theory ,homological algebra::18G Homological algebra [Classificació AMS] ,010307 mathematical physics ,Möbius inversion - Abstract
Decomposition spaces are simplicial $\infty$-groupoids subject to a certain exactness condition, needed to induce a coalgebra structure on the space of arrows. Conservative ULF functors (CULF) between decomposition spaces induce coalgebra homomorphisms. Suitable added finiteness conditions define the notion of M\"obius decomposition space, a far-reaching generalisation of the notion of M\"obius category of Leroux. In this paper, we show that the Lawvere-Menni Hopf algebra of M\"obius intervals, which contains the universal M\"obius function (but is not induced by a M\"obius category), can be realised as the homotopy cardinality of a M\"obius decomposition space $U$ of all M\"obius intervals, and that in a certain sense $U$ is universal for M\"obius decomposition spaces and CULF functors., Comment: 35 pages. This paper is one of six papers that formerly constituted the long manuscript arXiv:1404.3202. v3: minor expository improvements. Final version to appear in Adv. Math
- Published
- 2018
12. The spaces of B(r,s,t,u) strongly almost convergent double sequences and matrix transformations
- Author
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Orhan Tuǧ
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Combinatorics ,Matrix difference equation ,Matrix (mathematics) ,Transformation matrix ,General Mathematics ,010102 general mathematics ,Domain (ring theory) ,0101 mathematics ,Space (mathematics) ,01 natural sciences ,Double sequence ,Mathematics - Abstract
Most recently, some new double sequence spaces B ( M u ) , B ( C ϑ ) where ϑ = { b , b p , r , f , f 0 } and B ( L q ) for 0 q ∞ have been introduced as the domain of four-dimensional generalized difference matrix B ( r , s , t , u ) in the double sequence spaces M u , C ϑ where ϑ = { b , b p , r , f , f 0 } and L q for 0 q ∞ , and some topological properties, dual spaces, some new four-dimensional matrix classes and matrix transformations related to these spaces have also been studied by Tug and Basar and Tug (see [1] , [2] , [3] , [4] ). In this paper, we introduce new strongly almost convergent double sequence spaces B [ C f ] and B [ C f 0 ] whose B ( r , s , t , u ) -transforms are in the spaces [ C f ] and [ C f 0 ] , respectively. The main body of this paper is designed by the investigation of the following hypothesis. Firstly, we examine some topological properties and inclusion relations including the new double sequence spaces B [ C f ] and B [ C f 0 ] . Also, we determine the α-dual, β ( b p ) -dual and γ-dual of the space B [ C f ] . Finally, we give the necessary and sufficient conditions on an infinite matrix transforming from [ C f ] over C f , and we also characterize the classes ( [ C f ] ; M u ) , ( B [ C f ] ; C f ) and ( B [ C f ] ; M u ) .
- Published
- 2021
13. Involutions fixing Fn∪F3
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Pedro L. Q. Pergher and Évelin Meneguesso Barbaresco
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Combinatorics ,General Mathematics ,010102 general mathematics ,0103 physical sciences ,010307 mathematical physics ,Codimension ,0101 mathematics ,Fixed point ,01 natural sciences ,Mathematics - Abstract
Let M m be a closed smooth manifold equipped with a smooth involution having fixed point set of the form F n ∪ F 3 , where F n and F 3 are submanifolds with dimensions n and 3, respectively, where 3 n m and with the normal bundles over F n and F 3 being nonbounding. The authors of this paper, together with Patricia E. Desideri, previously showed that, when n is even, then m ≤ n + 4 , which we call a small codimension phenomenon. Further, they showed that this small bound is best possible. In this paper we study this problem for n odd, which is much more complicated, requiring more sophisticated techniques involving characteristic numbers. We show in this case that m ≤ M ( n − 3 ) + 6 , where M ( n ) is the Stong–Pergher number (see the definition of M ( n ) in Section 1). Further, we show that this bound is almost best possible, in the sense that there exists an example with m = M ( n − 3 ) + 5 , which means that for n odd the small codimension phenomenon does not occur and the bound in question is meaningful. The existence of these bounds is guaranteed by the famous Five Halves Theorem of J. Boardman, which establishes that, under the above hypotheses, m ≤ 5 2 n .
- Published
- 2018
14. Fonctions complètement multiplicatives de somme nulle
- Author
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Eric Saias and Jean-Pierre Kahane
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General Mathematics ,010102 general mathematics ,Multiplicative function ,01 natural sciences ,Abelian and tauberian theorems ,010101 applied mathematics ,Combinatorics ,symbols.namesake ,Riemann hypothesis ,Bounded function ,symbols ,Euler's formula ,0101 mathematics ,Invariant (mathematics) ,Well-defined ,Dirichlet series ,Mathematics - Abstract
Completely multiplicative functions whose sum is zero ($CMO$). The paper deals with $CMO$, meaning completely multiplicative ($CM$) functions $f$ such that $f(1)=1$ and $\sum\limits_1^\infty f(n)=0$. $CM$ means $f(ab)=f(a)f(b)$ for all $(a,b)\in \N^{*2}$, therefore $f$ is well defined by the $f(p)$, $p$ prime. Assuming that $f$ is $CM$, give conditions on the $f(p)$, either necessary or sufficient, both is possible, for $f$ being $CMO$ : that is the general purpose of the authors. The $CMO$ character of $f$ is invariant under slight modifications of the sequence $(f(p))$ (theorem~3). The same idea applies also in a more general context (theorem~4). After general statements of that sort, including examples of $CMO$ (theorem~5), the paper is devoted to ``small'' functions, that is, functions of the form $\frac{f(n)}{n}$, where the $f(n)$ are bounded. Here is a typical result : if $|f(p)|\le 1$ and $Re\, f(p)\le0$ for all $p$, a necessary and sufficient condition for $\big(\frac{f(n)}{n}\big)$ to be $CMO$ is $\sum \, Re\, f(p)/p=-\infty$ (theorem~8). Another necessary and sufficient condition is given under the assumption that $|1+f(p)|\le 1$ and $f(2)\not=-2$ (theorem~7). A third result gives only a sufficient condition (theorem~9). The three results apply to the particular case $f(p)=-1$, the historical example of Euler. Theorems 7 and 8 need auxiliary results, coming either from the existing literature (Hal\'asz, Montgomery--Vaughan), or from improved versions of classical results (Ingham, Ska\l ba) about $f(n)$ under assumptions on the $f*1(n)$, * denoting the multiplicative convolution (theorems~10~and~11).
- Published
- 2017
15. On the Taylor sequence spaces and upper boundedness of Hausdorff matrices and Nörlund matrices
- Author
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Gholamreza Talebi
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Sequence ,General Mathematics ,010102 general mathematics ,Hausdorff space ,010103 numerical & computational mathematics ,Space (mathematics) ,01 natural sciences ,Continuous functions on a compact Hausdorff space ,Sequence space ,law.invention ,Combinatorics ,Matrix (mathematics) ,Invertible matrix ,law ,0101 mathematics ,Normed vector space ,Mathematics - Abstract
In this paper, the Taylor sequence space t p θ of non-absolute type is introduced which consists of all sequences whose Taylor transforms of order θ , ( 0 θ 1 ) , are in the space l p . It is shown that the space t p θ is a normed space which includes the space l p where 1 ≤ p ≤ ∞ . Moreover, in this paper a general upper estimate is obtained for the norm of Hausdorff matrices and Norlund matrices as operators from l p into the Taylor sequence space t p θ . Finally, the results are extended to the matrix domain of an arbitrary invertible matrix E in the sequence space l p .
- Published
- 2017
16. Answer to a 1962 question by Zappa on cosets of Sylow subgroups
- Author
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Marston Conder
- Subjects
0301 basic medicine ,Pure mathematics ,Complement (group theory) ,Finite group ,Janko group ,General Mathematics ,010102 general mathematics ,Sylow theorems ,01 natural sciences ,Combinatorics ,03 medical and health sciences ,Normal p-complement ,030104 developmental biology ,Locally finite group ,Order (group theory) ,0101 mathematics ,Zappa–Szép product ,Mathematics - Abstract
In a paper in 1962, Guido Zappa asked whether a non-trivial coset of a Sylow p-subgroup of a finite group could contain only elements whose orders are powers of p, and also in that case, at least one element of order p. The first question was raised again recently in a 2014 paper by Daniel Goldstein and Robert Guralnick, when generalising an answer by John Thompson in 1967 to a similar question by L.J. Paige. In this paper we give a positive answer to both questions of Zappa, showing somewhat surprisingly that in a number of non-abelian finite simple groups (including PSL ( 3 , 4 ) , PSU ( 5 , 2 ) and the Janko group J 3 ), some non-trivial coset of a Sylow 5-subgroup (of order 5) contains only elements of order 5. Also Zappa's first question is studied in more detail. Various possibilities for the group and its Sylow p-subgroup P are eliminated, and it then follows that | P | ≥ 5 and | P | ≠ 8 . It is an open question as to whether the order of the Sylow p-subgroup can be 7 or 9 or more.
- Published
- 2017
17. Bilinear forms in Weyl sums for modular square roots and applications
- Author
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Igor E. Shparlinski, Alexander Dunn, Bryce Kerr, and Alexandru Zaharescu
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Conjecture ,Mathematics::Number Theory ,General Mathematics ,010102 general mathematics ,Bilinear form ,Siegel zero ,01 natural sciences ,Prime (order theory) ,Quadratic residue ,Combinatorics ,Quadratic equation ,Square root ,0103 physical sciences ,Quadratic field ,010307 mathematical physics ,0101 mathematics ,Mathematics - Abstract
Let q be a prime, P ⩾ 1 and let N q ( P ) denote the number of rational primes p ⩽ P that split in the imaginary quadratic field Q ( − q ) . The first part of this paper establishes various unconditional and conditional (under existence of a Siegel zero) lower bounds for N q ( P ) in the range q 1 / 4 + e ⩽ P ⩽ q , for any fixed e > 0 . This improves upon what is implied by work of Pollack and Benli–Pollack. The second part of this paper is dedicated to proving an estimate for a bilinear form involving Weyl sums for modular square roots (equivalently Salie sums). Our estimate has a power saving in the so-called Polya–Vinogradov range, and our methods involve studying an additive energy coming from quadratic residues in F q . This bilinear form is inspired by the recent automorphic motivation: the second moment for twisted L-functions attached to Kohnen newforms has recently been computed by the first and fourth authors. So the third part of this paper links the above two directions together and outlines the arithmetic applications of this bilinear form. These include the equidistribution of quadratic roots of primes, products of primes, and relaxations of a conjecture of Erdős–Odlyzko–Sarkozy.
- Published
- 2020
18. Exotic elliptic algebras of dimension 4
- Author
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Alexandru Chirvasitu and S. Paul Smith
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Discrete mathematics ,Ring (mathematics) ,General Mathematics ,010102 general mathematics ,Homogeneous coordinate ring ,Algebraic geometry ,Automorphism ,01 natural sciences ,Combinatorics ,Elliptic curve ,Grassmannian ,0103 physical sciences ,010307 mathematical physics ,0101 mathematics ,Algebraically closed field ,Incidence (geometry) ,Mathematics - Abstract
Let E be an elliptic curve defined over an algebraically closed field k whose characteristic is not 2 or 3. Let τ be a translation automorphism of E that is not of order 2. In a previous paper we studied an algebra A = A ( E , τ ) that depends on this data: A ( E , τ ) = ( S ( E , τ ) ⊗ M 2 ( k ) ) Γ where S ( E , τ ) is the 4-dimensional Sklyanin algebra associated to ( E , τ ) , M 2 ( k ) is the ring of 2 × 2 matrices over k, and Γ is ( Z / 2 ) × ( Z / 2 ) acting in a particular way as automorphisms of S and M 2 ( k ) . The action of Γ on S is compatible with the translation action of the 2-torsion subgroup E [ 2 ] on E. Following the ideas and results in papers of Artin–Tate–Van den Bergh, Smith–Stafford, and Levasseur–Smith, this paper examines the line modules, point modules, and fat point modules, over A, and their incidence relations. The right context for the results is non-commutative algebraic geometry: we view A as a homogeneous coordinate ring of a non-commutative analogue of P 3 that we denote by Proj n c ( A ) . Point modules and fat point modules determine “points” in Proj n c ( A ) . Line modules determine “lines” in Proj n c ( A ) . Line modules for A are in bijection with certain lines in P ( A 1 ⁎ ) ≅ P 3 and therefore correspond to the closed points of a certain subscheme L of the Grassmannian G ( 1 , 3 ) . Shelton–Vancliff call L the line scheme for A. We show that L is the union of 7 reduced and irreducible components, 3 quartic elliptic space curves and 4 plane conics in the ambient Plucker P 5 , and that deg ( L ) = 20 . The union of the lines corresponding to the points on each elliptic curve is an elliptic scroll in P ( A 1 ⁎ ) . Thus, the lines on that elliptic scroll are in natural bijection with a corresponding family of line modules for A.
- Published
- 2017
19. The other dual of MacMahon's theorem on plane partitions
- Author
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Mihai Ciucu
- Subjects
Combinatorics ,010201 computation theory & mathematics ,General Mathematics ,Lattice (order) ,010102 general mathematics ,Lattice line ,Hexagonal lattice ,0102 computer and information sciences ,0101 mathematics ,Equilateral triangle ,01 natural sciences ,Mathematics - Abstract
In this paper we introduce a counterpart structure to the shamrocks studied in the paper A dual of Macmahon's theorem on plane partitions by M. Ciucu and C. Krattenthaler (2013) [5] , which, just like the latter, can be included at the center of a lattice hexagon on the triangular lattice so that the region obtained from the hexagon by removing it has its number of lozenge tilings given by a simple product formula. The new structure, called a fern, consists of an arbitrary number of equilateral triangles of alternating orientations lined up along a lattice line. The shamrock and the fern seem to be the only such connected structures with this property. It would be interesting to understand the reason for this.
- Published
- 2017
20. Continued fractions and orderings on the Markov numbers
- Author
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Michelle Rabideau and Ralf Schiffler
- Subjects
Rational number ,Conjecture ,Mathematics - Number Theory ,Markov chain ,13F60, 11A55, 11B83, 30B70 ,General Mathematics ,Diophantine equation ,010102 general mathematics ,Mathematics - Rings and Algebras ,01 natural sciences ,Combinatorics ,Number theory ,Areas of mathematics ,Rings and Algebras (math.RA) ,0103 physical sciences ,FOS: Mathematics ,Mathematics - Combinatorics ,Combinatorics (math.CO) ,Number Theory (math.NT) ,010307 mathematical physics ,Uniqueness ,0101 mathematics ,Continuant (mathematics) ,Mathematics - Abstract
Markov numbers are integers that appear in the solution triples of the Diophantine equation, $x^2+y^2+z^2=3xyz$, called the Markov equation. A classical topic in number theory, these numbers are related to many areas of mathematics such as combinatorics, hyperbolic geometry, approximation theory and cluster algebras. There is a natural map from the rational numbers between zero and one to the Markov numbers. In this paper, we prove two conjectures seen in Martin Aigner's book, Markov's theorem and 100 years of the uniqueness conjecture, that determine an ordering on subsets of the Markov numbers based on their corresponding rational. The proof relies on a relationship between Markov numbers and continuant polynomials which originates in Frobenius' 1913 paper., 16 pages
- Published
- 2020
21. On the strong divergence of Hilbert transform approximations and a problem of Ul’yanov
- Author
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Holger Boche and Volker Pohl
- Subjects
Numerical Analysis ,Sequence ,Conjecture ,Applied Mathematics ,General Mathematics ,010102 general mathematics ,Mathematical analysis ,020206 networking & telecommunications ,02 engineering and technology ,01 natural sciences ,Combinatorics ,symbols.namesake ,Uniform norm ,Subsequence ,0202 electrical engineering, electronic engineering, information engineering ,symbols ,Hilbert transform ,0101 mathematics ,Divergence (statistics) ,Finite set ,Fourier series ,Analysis ,Mathematics - Abstract
This paper studies the approximation of the Hilbert transform f ? = H f of continuous functions f with continuous conjugate f ? based on a finite number of samples. It is known that every sequence { H N f } N ? N which approximates f ? from samples of f diverges (weakly) with respect to the uniform norm. This paper conjectures that all of these approximation sequences even contain no convergent subsequence. A property which is termed strong divergence.The conjecture is supported by two results. First it is proven that the sequence of the sampled conjugate Fejer means diverges strongly. Second, it is shown that for every sample based approximation method { H N } N ? N there are functions f such that ? H N f ? ∞ exceeds any given bound for any given number of consecutive indices N .As an application, the later result is used to investigate a problem associated with a question of Ul'yanov on Fourier series which is related to the possibility to construct adaptive approximation methods to determine the Hilbert transform from sampled data. This paper shows that no such approximation method with a finite search horizon exists.
- Published
- 2016
22. Kernel words and gap sequence of the tribonacci sequence
- Author
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Zhiying Wen and Yuke Huang
- Subjects
Discrete mathematics ,Sequence ,Kernel (set theory) ,General Mathematics ,Spectrum (functional analysis) ,General Physics and Astronomy ,Substitution (algebra) ,0102 computer and information sciences ,Fixed point ,01 natural sciences ,010101 applied mathematics ,Combinatorics ,010201 computation theory & mathematics ,Position (vector) ,0101 mathematics ,Alphabet ,Mathematics - Abstract
In this paper, we investigate the factor properties and gap sequence of the Tribonacci sequence, the fixed point of the substitution σ( a , b , c ) = ( ab , ac , a ). Let ω p be the p-th occurrence of ω and G p ( ω ) be the gap between ω p and ω p +1 . We introduce a notion of kernel for each factor ω , and then give the decomposition of the factor ω with respect to its kernel. Using the kernel and the decomposition, we prove the main result of this paper: for each factor ω , the gap sequence { G p ( ω )} p ≤1 is the Tribonacci sequence over the alphabet { G 1 ( ω ), G 2 ( ω ), G 4 ( ω )}, and the expressions of gaps are determined completely. As an application, for each factor ω and p ∈ ℕ , we determine the position of ω p . Finally we introduce a notion of spectrum for studying some typical combinatorial properties, such as power, overlap and separate of factors.
- Published
- 2016
23. A bound for Castelnuovo-Mumford regularity by double point divisors
- Author
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Sijong Kwak and Jinhyung Park
- Subjects
Conjecture ,Mathematics::Commutative Algebra ,General Mathematics ,010102 general mathematics ,14N05, 13D02, 14N25, 51N35 ,Vector bundle ,Codimension ,Mathematics - Commutative Algebra ,Commutative Algebra (math.AC) ,01 natural sciences ,Combinatorics ,Mathematics - Algebraic Geometry ,Mathematics::Algebraic Geometry ,Castelnuovo–Mumford regularity ,0103 physical sciences ,FOS: Mathematics ,010307 mathematical physics ,0101 mathematics ,Invariant (mathematics) ,Algebraically closed field ,Algebraic Geometry (math.AG) ,Projective variety ,Mathematics ,Counterexample - Abstract
Let $X \subseteq \mathbb{P}^r$ be a non-degenerate smooth projective variety of dimension $n$, codimension $e$, and degree $d$ defined over an algebraically closed field of characteristic zero. In this paper, we first show that $\text{reg} (\mathcal{O}_X) \leq d-e$, and classify the extremal and the next to extremal cases. Our result reduces the Eisenbud-Goto regularity conjecture for the smooth case to the problem finding a Castelnuovo-type bound for normality. It is worth noting that McCullough-Peeva recently constructed counterexamples to the regularity conjecture by showing that $\text{reg} (\mathcal{O}_X)$ is not even bounded above by any polynomial function of $d$ when $X$ is not smooth. For a normality bound in the smooth case, we establish that $\text{reg}(X) \leq n(d-2)+1$, which improves previous results obtained by Mumford, Bertram-Ein-Lazarsfeld, and Noma. Finally, by generalizing Mumford's method on double point divisors, we prove that $\text{reg}(X) \leq d-1+m$, where $m$ is an invariant arising from double point divisors associated to outer general projections. Using double point divisors associated to inner projection, we also obtain a slightly better bound for $\text{reg}(X)$ under suitable assumptions., Comment: 23 pages. This paper has been largely rewritten after McCullough-Peeva's counterexamples to the Eisenbud-Goto regularity conjecture, which appeared in J. Amer. Math. Soc. in 2018. We also added new results on the regularity of smooth projective varieties of arbitrary dimension
- Published
- 2020
24. Set relations and set systems induced by some families of integral domains
- Author
-
Paolo A. Oliverio, Federico Infusino, and Giampiero Chiaselotti
- Subjects
Endomorphism ,General Mathematics ,General problem ,Polynomial ring ,010102 general mathematics ,01 natural sciences ,Unitary state ,Integral domain ,Combinatorics ,0103 physical sciences ,Idempotence ,010307 mathematical physics ,Finitely-generated abelian group ,0101 mathematics ,U-1 ,Mathematics - Abstract
In this paper, given an integral domain U, we investigate the main properties of a relation ← m o d which is based on the interrelation between subdomains of U and finitely generated unitary submodules of U. We shall characterize it in terms of a second relation ≺ ⋄ between n-tuples ( u 1 , … , u n ) of elements of U and subdomains D of U defined by the vanishing in ( u 1 , … , u n ) of some polynomial p ( Z 1 , … , Z n ) belonging to a specific subset of the polynomial ring in several variables D [ Z 1 , … , Z n ] . Such an equivalence shall be used in order to introduce three specific collections of subdomains X U , B U and P U , whose algebraic properties present a close connection with geometrical and combinatorial properties induced by ← m o d . On the other hand, the characterization of the subdomains of X U leads to the more general problem of finding a map Ψ associating with a subdomain D of U a collection Ψ ( D ) of subdomains of K U such that the intersection of some or of any member of Ψ ( D ) gives D. In this perspective, in the present paper we shall study two further collections of subdomains of U, denoted respectively by E U and L U , whose main properties are related to those of the families P U and B U . Finally, our investigation of all the aforementioned subdomain families shall be also related to the study of pairs ( e , ξ ) , where e ∈ U ∖ { 0 } and ξ is an idempotent ring endomorphism of U whose kernel agrees with the ideal of U generated by e. We shall exhibit several results concerning the membership of ξ ( U ) and of ξ ( U ) [ e ] to the above subdomain families.
- Published
- 2020
25. Cohomology of the space of polynomial maps on A1 with prescribed ramification
- Author
-
Oishee Banerjee
- Subjects
Degree (graph theory) ,General Mathematics ,Ramification (botany) ,010102 general mathematics ,Étale cohomology ,Space (mathematics) ,01 natural sciences ,Cohomology ,Moduli space ,Combinatorics ,Mathematics::Algebraic Geometry ,Morphism ,0103 physical sciences ,010307 mathematical physics ,0101 mathematics ,Partially ordered set ,Mathematics - Abstract
In this paper we study the moduli spaces Simp n m of degree n + 1 morphisms A K 1 → A K 1 with “ramification length Simp n m is a Zariski open subset of the space of degree n + 1 polynomials over K up to A u t ( A K 1 ) . It is, in a way, orthogonal to the many papers about polynomials with prescribed zeroes- here we are prescribing, instead, the ramification data. Exploiting the topological properties of the poset that encodes the ramification behavior, we use a sheaf-theoretic argument to compute H ⁎ ( Simp n m ( C ) ; Q ) as well as the etale cohomology H e ´ t ⁎ ( Simp n m / K ; Q l ) for c h a r K = 0 or c h a r K > n + 1 , when n and m are such that n ≥ 3 m . As a by-product we obtain that H ⁎ ( Simp n m ( C ) ; Q ) is independent of n, thus implying rational cohomological stability. When c h a r K > 0 our methods compute H e ´ t ⁎ ( Simp n m ; Q l ) provided c h a r K > n + 1 and show that the etale cohomology groups in positive characteristics do not stabilize.
- Published
- 2020
26. Complexity testing techniques for time series data: A comprehensive literature review
- Author
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Lean Yu, Huiling Lv, Ling Tang, and Fengmei Yang
- Subjects
Theoretical computer science ,General Mathematics ,Applied Mathematics ,General Physics and Astronomy ,Statistical and Nonlinear Physics ,Space (mathematics) ,Chaos theory ,Combinatorics ,Nonlinear system ,Phase space ,Attractor ,Entropy (information theory) ,Time series ,Mathematics - Abstract
Complexity may be one of the most important measurements for analysing time series data; it covers or is at least closely related to different data characteristics within nonlinear system theory. This paper provides a comprehensive literature review examining the complexity testing techniques for time series data. According to different features, the complexity measurements for time series data can be divided into three primary groups, i.e., fractality (mono- or multi-fractality) for self-similarity (or system memorability or long-term persistence), methods derived from nonlinear dynamics (via attractor invariants or diagram descriptions) for attractor properties in phase-space, and entropy (structural or dynamical entropy) for the disorder state of a nonlinear system. These estimations analyse time series dynamics from different perspectives but are closely related to or even dependent on each other at the same time. In particular, a weaker self-similarity, a more complex structure of attractor, and a higher-level disorder state of a system consistently indicate that the observed time series data are at a higher level of complexity. Accordingly, this paper presents a historical tour of the important measures and works for each group, as well as ground-breaking and recent applications and future research directions.
- Published
- 2015
27. Optimization of Poincaré sections for discriminating between stochastic and deterministic behavior of dynamical systems
- Author
-
Krzysztof Michalak
- Subjects
Dynamical systems theory ,Series (mathematics) ,General Mathematics ,Applied Mathematics ,Evolutionary algorithm ,General Physics and Astronomy ,Statistical and Nonlinear Physics ,Type (model theory) ,Combinatorics ,symbols.namesake ,Dimension (vector space) ,Attractor ,Poincaré conjecture ,symbols ,Applied mathematics ,Poincaré map ,Mathematics - Abstract
This paper studies the problem of finding optimal parameters for a Poincare section used for determining the type of behavior of a time series: a deterministic or stochastic one. To reach that goal optimization algorithms are coupled with the Poincare & Higuchi (P&H) method, which calculates the Higuchi dimension using points obtained by performing a Poincare section of a certain attractor. The P&H method generates distinctive patterns that can be used for determining if a given attractor is produced by a deterministic or a stochastic system, but this method is sensitive to the parameters of the Poincare section. Patterns generated by the P&H method can be characterized using numerical measures which in turn can be used for finding such parameters for the Poincare section for which the patterns produced by the P&H method are the most prominent. This paper studies several approaches to parameterization of the Poincare section. Proposed approaches are tested on twelve time series, six produced by deterministic chaotic systems and six generated randomly. The obtained results show, that finding good parameters of the Poincare section is important for determining the type of behavior of a time series. Among the tested methods the evolutionary algorithm was able to find the best Poincare sections for use with the P&H method.
- Published
- 2015
28. A constant term approach to enumerating alternating sign trapezoids
- Author
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Ilse Fischer
- Subjects
Class (set theory) ,Plane (geometry) ,General Mathematics ,010102 general mathematics ,Center (group theory) ,01 natural sciences ,Column (database) ,Combinatorics ,Monotone polygon ,Operator (computer programming) ,Joint probability distribution ,0103 physical sciences ,010307 mathematical physics ,0101 mathematics ,Sign (mathematics) ,Mathematics - Abstract
We show that there is the same number of ( n , l ) -alternating sign trapezoids as there is of column strict shifted plane partitions of class l − 1 with at most n parts in the top row, thereby proving a result that was conjectured independently by Behrend and Aigner. The first objects generalize alternating sign triangles, which have recently been introduced by Ayyer, Behrend and the author who showed that they are counted by the same formula as alternating sign matrices. Column strict shifted plane partitions of a fixed class were introduced in a slightly different form by Andrews, and they essentially generalize descending plane partitions. They also correspond to cyclically symmetric lozenge tilings of a hexagon with a triangular hole in the center. In addition, we also provide three statistics on each class of objects and show that their joint distribution is the same. We prove our result by employing a constant term approach that is based on the author's operator formula for monotone triangles. This paper complements a forthcoming paper of Behrend and the author, where the six-vertex model approach is used to show equinumeracy as well as generalizations involving statistics that are different from those considered in the present paper.
- Published
- 2019
29. On the Peterson hit problem
- Author
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Nguyễn Sum
- Subjects
Combinatorics ,Set (abstract data type) ,Polynomial ,Steenrod algebra ,Degree (graph theory) ,General Mathematics ,FOS: Mathematics ,Algebraic Topology (math.AT) ,55S10 (Primary), 55S05, 55T15 (Secondary) ,Mathematics - Algebraic Topology ,Prime field ,Algebra over a field ,Mathematics - Abstract
We study the hit problem, set up by F. Peterson, of finding a minimal set of generators for the polynomial algebra $P_k := \mathbb F_2[x_1,x_2,...,x_k]$ as a module over the mod-2 Steenrod algebra, $\mathcal{A}$. In this paper, we study a minimal set of generators for $\mathcal A$-module $P_k$ in some so-call generic degrees and apply these results to explicitly determine the hit problem for $k=4$., Comment: 68 pages, Quy Nhon University preprint, Viet Nam, 2011. A shorter version of this paper was published in Advances in Mathematics
- Published
- 2015
30. Covering with universally Baire operators
- Author
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Grigor Sargsyan
- Subjects
Discrete mathematics ,Combinatorics ,Mathematics::Logic ,Transitive relation ,Conjecture ,Large cardinal ,General Mathematics ,Core model ,Inner model theory ,Axiom ,Mathematics ,Descriptive set theory - Abstract
We introduce a covering conjecture and show that it holds below A D R + “ Θ is regular” . We then use it to show that in the presence of mild large cardinal axioms, PFA implies that there is a transitive model containing the reals and ordinals and satisfying A D R + “ Θ is regular” . The method used to prove the Main Theorem of this paper is the core model induction. The paper contains the first application of the core model induction that goes significantly beyond the region of A D + + θ 0 Θ .
- Published
- 2015
31. Fast CBC construction of randomly shifted lattice rules achievingO(n−1+δ)convergence for unbounded integrands overRsin weighted spaces with POD weights
- Author
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Frances Y. Kuo and James A. Nichols
- Subjects
Statistics and Probability ,Numerical Analysis ,Control and Optimization ,Algebra and Number Theory ,Function space ,Applied Mathematics ,General Mathematics ,Cumulative distribution function ,Univariate ,Inverse ,Probability density function ,Sobolev space ,Combinatorics ,Unit cube ,Lattice (order) ,Mathematics - Abstract
This paper provides the theoretical foundation for the component-by-component (CBC) construction of randomly shifted lattice rules that are tailored to integrals over R s arising from practical applications. For an integral of the form ∫ R s f ( y ) ∏ j = 1 s ϕ ( y j ) d y with a univariate probability density ϕ , our general strategy is to first map the integral into the unit cube [ 0 , 1 ] s using the inverse of the cumulative distribution function of ϕ , and then apply quasi-Monte Carlo (QMC) methods. However, the transformed integrand in the unit cube rarely falls within the standard QMC setting of Sobolev spaces of functions with mixed first derivatives. Therefore, a non-standard function space setting for integrands over R s , previously considered by Kuo, Sloan, Wasilkowski and Waterhouse (2010), is required for the analysis. Motivated by the needs of three applications, the present paper extends the theory of the aforementioned paper in several non-trivial directions, including a new error analysis for the CBC construction of lattice rules with general non-product weights, the introduction of an unanchored variant for the setting, the use of coordinate-dependent weight functions in the norm, and the strategy for fast CBC construction with POD (“product and order dependent”) weights.
- Published
- 2014
32. Central sets and substitutive dynamical systems
- Author
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Marcy Barge and Luca Q. Zamboni
- Subjects
medicine.medical_specialty ,Pure mathematics ,Conjecture ,Dynamical systems theory ,General Mathematics ,ta111 ,010102 general mathematics ,Mathematics::General Topology ,Topological dynamics ,0102 computer and information sciences ,Fixed point ,01 natural sciences ,Combinatorics ,Combinatorics on words ,Areas of mathematics ,010201 computation theory & mathematics ,Idempotence ,medicine ,Arithmetic function ,0101 mathematics ,Mathematics - Abstract
In this paper we establish a new connection between central sets and the strong coincidence conjecture for fixed points of irreducible primitive substitutions of Pisot type. Central sets, first introduced by Furstenberg using notions from topological dynamics, constitute a special class of subsets of N possessing strong combinatorial properties: Each central set contains arbitrarily long arithmetic progressions, and solutions to all partition regular systems of homogeneous linear equations. We give an equivalent reformulation of the strong coincidence condition in terms of central sets and minimal idempotent ultrafilters in the Stone–Cech compactification β N . This provides a new arithmetical approach to an outstanding conjecture in tiling theory, the Pisot substitution conjecture. The results in this paper rely on interactions between different areas of mathematics, some of which had not previously been directly linked: They include the general theory of combinatorics on words, abstract numeration systems, tilings, topological dynamics and the algebraic/topological properties of Stone–Cech compactification of N .
- Published
- 2013
33. The representation of the symmetric group on m -Tamari intervals
- Author
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Louis-François Préville-Ratelle, Mireille Bousquet-Mélou, Guillaume Chapuy, Laboratoire Bordelais de Recherche en Informatique (LaBRI), Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB), Laboratoire d'informatique Algorithmique : Fondements et Applications (LIAFA), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de combinatoire et d'informatique mathématique [Montréal] (LaCIM), Centre de Recherches Mathématiques [Montréal] (CRM), Université de Montréal (UdeM)-Université de Montréal (UdeM)-Université du Québec à Montréal = University of Québec in Montréal (UQAM), European Project: 208471,EC:FP7:ERC,ERC-2007-StG,EXPLOREMAPS(2008), and Université de Bordeaux (UB)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Enumeration ,Tamari lattices ,General Mathematics ,Lattice (group) ,0102 computer and information sciences ,01 natural sciences ,Combinatorics ,Permutation ,Symmetric group ,[MATH.MATH-CO]Mathematics [math]/Combinatorics [math.CO] ,FOS: Mathematics ,Mathematics - Combinatorics ,0101 mathematics ,Representations of the symmetric group ,Mathematics ,Discrete mathematics ,Sequence ,Mathematics::Combinatorics ,010102 general mathematics ,Generating function ,Lattice paths ,010201 computation theory & mathematics ,Iterated function ,Bijection ,Combinatorics (math.CO) ,MCS 05A15, 05E18, 20C30 ,Parking functions ,Tamari lattice - Abstract
An m-ballot path of size n is a path on the square grid consisting of north and east unit steps, starting at (0,0), ending at (mn,n), and never going below the line {x=my}. The set of these paths can be equipped with a lattice structure, called the m-Tamari lattice and denoted by T_n^{m}, which generalizes the usual Tamari lattice T_n obtained when m=1. This lattice was introduced by F. Bergeron in connection with the study of diagonal coinvariant spaces in three sets of n variables. The representation of the symmetric group S_n on these spaces is conjectured to be closely related to the natural representation of S_n on (labelled) intervals of the m-Tamari lattice, which we study in this paper. An interval [P,Q] of T_n^{m} is labelled if the north steps of Q are labelled from 1 to n in such a way the labels increase along any sequence of consecutive north steps. The symmetric group S_n acts on labelled intervals of T_n^{m} by permutation of the labels. We prove an explicit formula, conjectured by F. Bergeron and the third author, for the character of the associated representation of S_n. In particular, the dimension of the representation, that is, the number of labelled m-Tamari intervals of size n, is found to be (m+1)^n(mn+1)^{n-2}. These results are new, even when m=1. The form of these numbers suggests a connection with parking functions, but our proof is not bijective. The starting point is a recursive description of m-Tamari intervals. It yields an equation for an associated generating function, which is a refined version of the Frobenius series of the representation. This equation involves two additional variables x and y, a derivative with respect to y and iterated divided differences with respect to x. The hardest part of the proof consists in solving it, and we develop original techniques to do so, partly inspired by previous work on polynomial equations with "catalytic" variables., Comment: 29 pages --- This paper subsumes the research report arXiv:1109.2398, which will not be submitted to any journal
- Published
- 2013
34. Integral affine Schur–Weyl reciprocity
- Author
-
Qiang Fu
- Subjects
Surjective function ,Combinatorics ,Quantum affine algebra ,Algebra homomorphism ,Loop algebra ,General Mathematics ,Quiver ,Universal enveloping algebra ,Affine transformation ,Schur algebra ,Mathematics - Abstract
Let D ▵ ( n ) be the double Ringel–Hall algebra of the cyclic quiver △ ( n ) and let D ▵ ( n ) be the modified quantum affine algebra of D ▵ ( n ) . We will construct an integral form D ▵ ( n ) Z for D ▵ ( n ) such that the natural algebra homomorphism from D ▵ ( n ) Z to the integral affine quantum Schur algebra is surjective. Furthermore, we will use Hall algebras to construct the integral form U Z ( g l n ) of the universal enveloping algebra U ( g l n ) of the loop algebra g l n = g l n ( Q ) ⊗ Q [ t , t − 1 ] , and prove that the natural algebra homomorphism from U Z ( g l n ) to the affine Schur algebra over Z is surjective. In a subsequent paper (Fu [10] ), we will use affine Schur algebras to give BLM realization of U Z ( g l n ) , and this enables us to give a new proof of the statements about U Z ( g l n ) given in this paper.
- Published
- 2013
35. Generalized Hilbert operators on weighted Bergman spaces
- Author
-
Jouni Rättyä and José Ángel Peláez
- Subjects
Weight function ,Mathematics - Complex Variables ,General Mathematics ,010102 general mathematics ,Mathematical analysis ,01 natural sciences ,Combinatorics ,Compact space ,Type condition ,Operator (computer programming) ,Bergman space ,Bounded function ,0103 physical sciences ,010307 mathematical physics ,0101 mathematics ,Connection (algebraic framework) ,Primary 30H20, Secondary 47G10 ,Mathematics - Abstract
The main purpose of this paper is to study the generalized Hilbert operator {equation*} \mathcal{H}_g(f)(z)=\int_0^1f(t)g'(tz)\,dt {equation*} acting on the weighted Bergman space $A^p_\om$, where the weight function $\om$ belongs to the class $\R$ of regular radial weights and satisfies the Muckenhoupt type condition {equation}\label{Mpconditionaabstract} \sup_{0\le r, Comment: This paper has been accepted for publication in Advances in Mathematics
- Published
- 2013
36. Partial rigidity of degenerate CR embeddings into spheres
- Author
-
Peter Ebenfelt
- Subjects
Mathematics - Differential Geometry ,Mathematics - Complex Variables ,General Mathematics ,Second fundamental form ,Degenerate energy levels ,Combinatorics ,32H02, 32V30 ,Hypersurface ,Rigidity (electromagnetism) ,Differential Geometry (math.DG) ,Complex space ,FOS: Mathematics ,Covariant transformation ,SPHERES ,Complex Variables (math.CV) ,Complex plane ,Mathematics - Abstract
In this paper, we study degenerate CR embeddings f of a strictly pseudoconvex hypersurface M ⊂ C n + 1 into a sphere S in a higher dimensional complex space C N + 1 . The degeneracy of the mapping f will be characterized in terms of the ranks of the CR second fundamental form and its covariant derivatives. In 2004, the author, together with X. Huang and D. Zaitsev, established a rigidity result for CR embeddings f into spheres in low codimensions. A key step in the proof of this result was to show that degenerate mappings are necessarily contained in a complex plane section of the target sphere (partial rigidity). In the 2004 paper, it was shown that if the total rank d of the second fundamental form and all of its covariant derivatives is n (here, n is the CR dimension of M ), then f ( M ) is contained in a complex plane of dimension n + d + 1 . The converse of this statement is also true, as is easy to see. When the total rank d exceeds n , it is no longer true, in general, that f ( M ) is contained in a complex plane of dimension n + d + 1 , as can be seen by examples. In this paper, we carry out a systematic study of degenerate CR mappings into spheres. We show that when the ranks of the second fundamental form and its covariant derivatives exceed the CR dimension n , then partial rigidity may still persist, but there is a “defect” k that arises from the ranks exceeding n such that f ( M ) is only contained in a complex plane of dimension n + d + k + 1 . Moreover, this defect occurs in general, as is illustrated by examples.
- Published
- 2013
37. Minimal subsystems of triangular maps of type 2∞; Conclusion of the Sharkovsky classification program
- Author
-
Tomasz Downarowicz
- Subjects
Discrete mathematics ,Conjecture ,General Mathematics ,Applied Mathematics ,General Physics and Astronomy ,Statistical and Nonlinear Physics ,Special class ,Odometer ,Toeplitz matrix ,Combinatorics ,Positive entropy ,ComputingMethodologies_SYMBOLICANDALGEBRAICMANIPULATION ,Embedding ,Entropy (information theory) ,Topological conjugacy ,Mathematics - Abstract
The subject of this paper is to give the description, up to topological conjugacy, of possible minimal sets of triangular maps of the square of type 2 ∞ . In [4] , we give a general method allowing to embed any zero-dimensional almost 1–1 extension of the dyadic odometer (in particular any dyadic Toeplitz system) as a minimal set of a triangular map of this type. In this paper we present a method (a combination of that described in [4] with one introduced in [1] ) of similarly embedding a special class of zero-dimensional almost 2–1 extensions of the odometer. We conjecture that these two embedding theorems exhaust all possibilities for nonperiodic minimal sets. The paper was inspired by the last unsolved problem in the Sharkovski classification program of triangular maps: does there exist a triangular map with positive entropy attained on the set of uniformly recurrent points but with entropy zero on the set of regularly recurrent points. The paper answers this question positively, concluding the program.
- Published
- 2013
38. Topological Hausdorff dimension and level sets of generic continuous functions on fractals
- Author
-
Richárd Balka, Márton Elekes, and Zoltán Buczolich
- Subjects
Discrete mathematics ,28A78, 28A80, 26A99 ,Continuous function ,General Mathematics ,Applied Mathematics ,General Topology (math.GN) ,Hausdorff space ,Mathematics::General Topology ,General Physics and Astronomy ,Statistical and Nonlinear Physics ,Topology ,Combinatorics ,Metric space ,Hausdorff distance ,Fractal ,Compact space ,Mathematics - Classical Analysis and ODEs ,Hausdorff dimension ,Totally disconnected space ,Classical Analysis and ODEs (math.CA) ,FOS: Mathematics ,Mathematics::Metric Geometry ,Mathematics - General Topology ,Mathematics - Abstract
In an earlier paper (arxiv:1108.4292) we introduced a new concept of dimension for metric spaces, the so called topological Hausdorff dimension. For a compact metric space $K$ let $\dim_{H}K$ and $\dim_{tH} K$ denote its Hausdorff and topological Hausdorff dimension, respectively. We proved that this new dimension describes the Hausdorff dimension of the level sets of the generic continuous function on $K$, namely $\sup{\dim_{H}f^{-1}(y) : y \in \mathbb{R}} = \dim_{tH} K - 1$ for the generic $f \in C(K)$, provided that $K$ is not totally disconnected, otherwise every non-empty level set is a singleton. We also proved that if $K$ is not totally disconnected and sufficiently homogeneous then $\dim_{H}f^{-1}(y) = \dim_{tH} K - 1$ for the generic $f \in C(K)$ and the generic $y \in f(K)$. The most important goal of this paper is to make these theorems more precise. As for the first result, we prove that the supremum is actually attained on the left hand side of the first equation above, and also show that there may only be a unique level set of maximal Hausdorff dimension. As for the second result, we characterize those compact metric spaces for which for the generic $f\in C(K)$ and the generic $y\in f(K)$ we have $\dim_{H} f^{-1}(y)=\dim_{tH}K-1$. We also generalize a result of B. Kirchheim by showing that if $K$ is self-similar then for the generic $f\in C(K)$ for every $y\in \inter f(K)$ we have $\dim_{H} f^{-1}(y)=\dim_{tH}K-1$. Finally, we prove that the graph of the generic $f\in C(K)$ has the same Hausdorff and topological Hausdorff dimension as $K$., 20 pages
- Published
- 2012
39. The Spaces of Cesàro Almost Convergent Sequences and Core Theorems
- Author
-
Mehmet Şengönül and Kuddusi Kayaduman
- Subjects
Combinatorics ,Discrete mathematics ,Matrix (mathematics) ,Sequence ,General Mathematics ,Core (graph theory) ,General Physics and Astronomy ,Order (group theory) ,Field (mathematics) ,Isomorphism ,Space (mathematics) ,Sequence space ,Mathematics - Abstract
As known, the method to obtain a sequence space by using convergence field of an infinite matrix is an old method in the theory of sequence spaces. However, the study of convergence field of an infinite matrix in the space of almost convergent sequences is so new (see [15]). The purpose of this paper is to introduce the new spaces and consisting of all sequences whose Cesaro transforms of order one are in the spaces f and f0, respectively. Also, in this paper, we show that and are linearly isomorphic to the spaces f and f0, respectively. The β- and γ-duals of the spaces and are computed. Furthermore, the classes ( : μ) and (μ: ) of infinite matrices are characterized for any given sequence space μ, and determined the necessary and sufficient conditions on a matrix A to satisfy BC-core(Ax) ⊆ K-core(x), K-core(Ax) ⊆ BC-core(x), BC-core(Ax) ⊆ BC-core(x), BC-core(Ax) ⊆ st-core(x) for all x ∈ l∈.
- Published
- 2012
40. On the centre of a vector lattice
- Author
-
Elmiloud Chil and Mathieu Meyer
- Subjects
Combinatorics ,Lattice (module) ,Pure mathematics ,Reciprocal lattice ,Vector lattice ,Locally convex vector lattice ,General Mathematics ,Integer lattice ,Structure (category theory) ,Orthomorphism ,Centre ,Mathematics - Abstract
This paper is mainly concerned with the structure of the centre of a vector lattice. A special attention is paid in the case when E = L p , p ≥ 1 . In this paper we give some characterizations of dense vector sublattices of the centre. Those characterizations will be applied in several directions. At the end of this work we compare various fullness and richness properties of the centre of a vector lattice.
- Published
- 2012
41. A binding number condition for graphs to be (a,b,k)-critical graphs
- Author
-
Lan Xu, Jiashang Jiang, and Sizhong Zhou
- Subjects
Combinatorics ,Discrete mathematics ,Integer ,Binding number ,[a,b]-Factor ,General Mathematics ,(a,b,k)-Critical graph ,Graph ,Mathematics - Abstract
Let a and b be two even integers with 2 ⩽ a < b, and let k be a nonnegative integer. Let G be a graph of order n. Its binding number bind(G) is defined as follows, bind(G)=min|NG(X)||X|:∅≠X⊆V(G),NG(X)≠V(G). In this paper, it is proved that G is an (a, b, k)-critical graph if bind(G)>(a+b-1)(n-1)bn-(a+b)-bk+3 and n⩾(a+b)(a+b-3)b+bkb-1. Furthermore, it is shown that the result in this paper is best possible in some sense.
- Published
- 2012
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42. The generalized inverses of differentiation and integration
- Author
-
Steven H. Weintraub
- Subjects
Combinatorics ,Degree (graph theory) ,General Mathematics ,Operator (physics) ,Product (mathematics) ,Legendre polynomials ,Vector space ,Mathematics - Abstract
Let P n be the vector space of polynomials of degree at most n , equipped with the inner product 〈 f , g 〉 = ∫ − 1 1 f ( x ) g ( x ) d x . Let D : P n ⟶ P n − 1 be the differentiation operator and I : P n − 1 ⟶ P n be the integration operator. In this paper the generalized (Moore–Penrose) inverses of D and I are computed. The answer for D is straightforward, though perhaps somewhat unexpected. The answer for I requires more work, and involves Legendre polynomials in an unexpected way.
- Published
- 2021
43. Best approximation in polyhedral Banach spaces
- Author
-
Libor Veselý, Joram Lindenstrauss, and Vladimir P. Fonf
- Subjects
Mathematics(all) ,Numerical Analysis ,Applied Mathematics ,General Mathematics ,Mathematical analysis ,Banach space ,Hausdorff space ,Metric projection ,Codimension ,Geometric property ,Proximinal subspace ,Combinatorics ,Polyhedral Banach space ,Norm (mathematics) ,Analysis ,Subspace topology ,Quotient ,Mathematics - Abstract
In the present paper, we study conditions under which the metric projection of a polyhedral Banach space X onto a closed subspace is Hausdorff lower or upper semicontinuous. For example, we prove that if X satisfies (*) (a geometric property stronger than polyhedrality) and Y@?X is any proximinal subspace, then the metric projection P"Y is Hausdorff continuous and Y is strongly proximinal (i.e., if {y"n}@?Y, x@?X and @?y"n-x@?->dist(x,Y), then dist(y"n,P"Y(x))->0). One of the main results of a different nature is the following: if X satisfies (*) and Y@?X is a closed subspace of finite codimension, then the following conditions are equivalent: (a) Y is strongly proximinal; (b) Y is proximinal; (c) each element of Y^@? attains its norm. Moreover, in this case the quotient X/Y is polyhedral. The final part of the paper contains examples illustrating the importance of some hypotheses in our main results.
- Published
- 2011
44. On the effectiveness of a generalization of Miller’s primality theorem
- Author
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Zhenxiang Zhang
- Subjects
Statistics and Probability ,Numerical Analysis ,Control and Optimization ,Algebra and Number Theory ,Applied Mathematics ,General Mathematics ,Primality certificate ,Solovay–Strassen primality test ,Algebra ,Combinatorics ,Miller–Rabin primality test ,Strong pseudoprime ,Primality test ,Provable prime ,Industrial-grade prime ,Mathematics ,Lucas primality test - Abstract
Berrizbeitia and Olivieri showed in a recent paper that, for any integer r, the notion of @w-prime to base a leads to a primality test for numbers n=1 mod r, that under the Extended Riemann Hypothesis (ERH) runs in polynomial time. They showed that the complexity of their test is at most the complexity of the Miller primality test (MPT), which is O((logn)^4^+^o^(^1^)). They conjectured that their test is more effective than the MPT if r is large. In this paper, we show that their conjecture is not true by showing that the Berrizbeitia-Olivieri primality test (BOPT) has no advantage over the MPT, either for proving primality of a prime under the ERH, or for detecting compositeness of a composite. In particular, we point out that the complexity of the BOPT depends not only on n but also on r and that in the worst cases (usually when n is prime) for both tests, the BOPT is in general at least twice slower than the MPT, and in some cases (usually when n is composite) the BOPT may be much slower. Moreover, the BOPT needs O(rlogn) bit memories. We also give facts and numerical examples to show that, for some composites n and for some r, the rth roots of unity @w do not exist, and thus outputs of the BOPT are ERH conditional, whereas the MPT always quickly and definitely (without ERH) detects compositeness for all odd composites.
- Published
- 2010
45. On strata of degenerate polyhedral cones, II: Relations between condition measures
- Author
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Felipe Cucker, Javier Peña, and Dennis Cheung
- Subjects
Statistics and Probability ,Numerical Analysis ,021103 operations research ,Control and Optimization ,Algebra and Number Theory ,Condition numbers ,Applied Mathematics ,General Mathematics ,0211 other engineering and technologies ,010103 numerical & computational mathematics ,02 engineering and technology ,01 natural sciences ,Combinatorics ,Complementarity problems ,Linear programming ,0101 mathematics ,Mathematics - Abstract
In a paper Cheung, Cucker and Peña (in press) [5] that can be seen as the first part of this one, we extended the well-known condition numbers for polyhedral conic systems C(A) Renegar (1994, 1995) [7–9] and C(A) Cheung and Cucker (2001) [3] to versions C¯(A) and C¯(A) that are finite for all input matrices A∈Rn×m. In this paper we compare C¯(A) and C¯(A) with other condition measures for the same problem that are also always finite.
- Published
- 2010
46. Generation of fractals from complex logistic map
- Author
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Mamta Rani and Rashi Agarwal
- Subjects
Discrete dynamics ,General Mathematics ,Applied Mathematics ,General Physics and Astronomy ,Inverse ,Statistical and Nonlinear Physics ,Mandelbrot set ,Julia set ,Combinatorics ,Fractal ,Iterated function ,Bounded function ,Logistic map ,Mathematics - Abstract
Remarkably benign looking logistic transformations x n +1 = r x n (1 − x n ) for choosing x 0 between 0 and 1 and 0 r ⩽ 4 have found a celebrated place in chaos, fractals and discrete dynamics. The strong physical meaning of Mandelbrot and Julia sets is broadly accepted and nicely connected by Christian Beck [Beck C. Physical meaning for Mandelbrot and Julia sets. Physica D 1999;125(3–4):171–182. Zbl0988.37060] to the complex logistic maps, in the former case, and to the inverse complex logistic map, in the latter case. The purpose of this paper is to study the bounded behavior of the complex logistic map using superior iterates and generate fractals from the same. The analysis in this paper shows that many beautiful properties of the logistic map are extendable for a larger value of r .
- Published
- 2009
47. The Lebesgue measure of the algebraic difference of two random Cantor sets
- Author
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Boris Solomyak, Péter Móra, and Károly Simon
- Subjects
Discrete mathematics ,Mathematics(all) ,Lebesgue measure ,General Mathematics ,010102 general mathematics ,Cantor function ,Random fractals ,01 natural sciences ,Point process ,Cantor set ,Combinatorics ,Null set ,010104 statistics & probability ,symbols.namesake ,Difference of Cantor sets ,Palis conjecture ,Branching processes with random environment ,symbols ,Random compact set ,Almost surely ,0101 mathematics ,Cantor's diagonal argument ,Mathematics - Abstract
In this paper we consider a family of random Cantor sets on the line. We give some sufficient conditions when the Lebesgue measure of the arithmetic difference is positive. Combining this with the main result of a recent joint paper of the second author with M. Dekking we construct random Cantor sets F1, F2 such that the arithmetic difference set F2 − F1 does not contain any intervals but ℒeb(F2 − F1)> 0 almost surely, conditioned on non-extinction.
- Published
- 2009
- Full Text
- View/download PDF
48. A Birkhoff–Bruhat atlas for partial flag varieties
- Author
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Xuhua He and Huanchen Bao
- Subjects
Index set (recursion theory) ,Mathematics::Combinatorics ,Atlas (topology) ,Group (mathematics) ,General Mathematics ,010102 general mathematics ,010103 numerical & computational mathematics ,Reductive group ,01 natural sciences ,Stratification (mathematics) ,Combinatorics ,Bruhat decomposition ,Mathematics::Quantum Algebra ,0101 mathematics ,Variety (universal algebra) ,Mathematics::Representation Theory ,Flag (geometry) ,Mathematics - Abstract
A partial flag variety P K of a Kac–Moody group G has a natural stratification into projected Richardson varieties. When G is a connected reductive group, a Bruhat atlas for P K was constructed in He et al. (2013): P K is locally modelled with Schubert varieties in some Kac–Moody flag variety as stratified spaces. The existence of Bruhat atlases implies some nice combinatorial and geometric properties on the partial flag varieties and the decomposition into projected Richardson varieties. A Bruhat atlas does not exist for partial flag varieties of an arbitrary Kac–Moody group due to combinatorial and geometric reasons. To overcome obstructions, we introduce the notion of Birkhoff–Bruhat atlas. Instead of the Schubert varieties used in a Bruhat atlas, we use the J -Schubert varieties for a Birkhoff–Bruhat atlas. The notion of the J -Schubert varieties interpolates Birkhoff decomposition and Bruhat decomposition of the full flag variety (of a larger Kac–Moody group). The main result of this paper is the construction of a Birkhoff–Bruhat atlas for any partial flag variety P K of a Kac–Moody group. We also construct a combinatorial atlas for the index set Q K of the projected Richardson varieties in P K . As a consequence, we show that Q K has some nice combinatorial properties. This gives a new proof and generalizes the work of Williams (2007) in the case where the group G is a connected reductive group.
- Published
- 2021
49. The rate of convergence for the cyclic projections algorithm III: Regularity of convex sets
- Author
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Hein Hundal and Frank Deutsch
- Subjects
Mathematics(all) ,Alternating projections ,General Mathematics ,Convex feasibility problem ,0211 other engineering and technologies ,02 engineering and technology ,01 natural sciences ,Cyclic projections ,POCS ,Combinatorics ,symbols.namesake ,Intersection ,Angle between subspaces ,Projections onto convex sets ,0101 mathematics ,Mathematics ,Numerical Analysis ,021103 operations research ,Series (mathematics) ,Applied Mathematics ,010102 general mathematics ,Hilbert space ,Regular polygon ,Orthogonal projections ,Angle between convex sets ,Rate of convergence ,The strong conical hull intersection property (strong CHIP) ,Norm of nonlinear operators ,Iterated function ,Norm (mathematics) ,symbols ,Algorithm ,Analysis ,Regularity properties of convex sets: regular, linearly regular, boundedly regular, boundedly linearly regular, normal, weakly normal, uniformly normal - Abstract
The cyclic projections algorithm is an important method for determining a point in the intersection of a finite number of closed convex sets in a Hilbert space. That is, for determining a solution to the ''convex feasibility'' problem. This is the third paper in a series on a study of the rate of convergence for the cyclic projections algorithm. In the first of these papers, we showed that the rate could be described in terms of the ''angles'' between the convex sets involved. In the second, we showed that these angles often had a more tractable formulation in terms of the ''norm'' of the product of the (nonlinear) metric projections onto related convex sets. In this paper, we show that the rate of convergence of the cyclic projections algorithm is also intimately related to the ''linear regularity property'' of Bauschke and Borwein, the ''normal property'' of Jameson (as well as Bakan, Deutsch, and Li's generalization of Jameson's normal property), the ''strong conical hull intersection property'' of Deutsch, Li, and Ward, and the rate of convergence of iterated parallel projections. Such properties have already been shown to be important in various other contexts as well.
- Published
- 2008
50. Generalized radix representations and dynamical systems. IV
- Author
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Jörg M. Thuswaldner, Attila Pethő, Shigeki Akiyama, and Horst Brunotte
- Subjects
Mathematics(all) ,Pure mathematics ,Pisot–Vijayaraghavan number ,Distribution (number theory) ,Series (mathematics) ,Pisot number ,General Mathematics ,Periodic point ,Function (mathematics) ,Contracting polynomial ,Fractional part ,Beta expansion ,Canonical number system ,Combinatorics ,Természettudományok ,Integer ,Radix ,Matematika- és számítástudományok ,Mathematics - Abstract
For r = ( r 1 ,…, r d ) ∈ ℝ d the mapping τ r :ℤ d →ℤ d given by τ r ( a 1 ,…, a d ) = ( a 2 , …, a d ,−⌊ r 1 a 1 +…+ r d a d ⌋) where ⌊·⌋ denotes the floor function, is called a shift radix system if for each a ∈ ℤ d there exists an integer k > 0 with τ r k ( a ) = 0. As shown in Part I of this series of papers, shift radix systems are intimately related to certain well-known notions of number systems like β -expansibns and canonical number systems. After characterization results on shift radix systems in Part II of this series of papers and the thorough investigation of the relations between shift radix systems and canonical number systems in Part III, the present part is devoted to further structural relationships between shift radix systems and β -expansions. In particular we establish the distribution of Pisot polynomials with and without the finiteness property (F).
- Published
- 2008
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