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A symmetric planar central configuration of the Newtonian six-body problem x is called cross central configuration if there are precisely four bodies on a symmetry line of x. We use complex algebraic geometry and Groebner basis theory to prove that for a generic choice of positive real masses $$m_1,m_2,m_3,m_4,m_5=m_6$$ there is a finite number of cross central configurations. We also show one explicit example of a configuration in this class. A part of our approach is based on relaxing the output of the Groebner basis computations. This procedure allows us to obtain upper bounds for the dimension of an algebraic variety. We get the same results considering cross central configurations of the six-vortex problem.

This thesis is dedicated to the constructions of modular lattices with algebraic methods. The goal is to develop new methods as well as constructing new lattices. There are three methods considered: construction from number fields, construction from totally definite quaternion algebras over number fields and construction from linear codes via generalized Construction A. The construction of Arakelov-modular lattices, which result in modular lattices, was first introduced in [6] for ideal lattices from cyclotomic fields. We generalize this construction to other number fields and also to totally definite quaternion algebras over number fields. We give the characterization of Arakelov-modular lattices over the maximal real subfield of a cyclotomic field with prime power degree and totally real Galois fields with odd degrees. Characterizations of Arakelov-modular lattices of trace type, which are special cases of Arakelov- modular lattices, are given for quadratic fields and maximal real subfields of cyclotomic fields with non-prime power degrees. Furthermore, we give the classification of Arakelov-modular lattices of level l for l a prime over totally definite quaternion algebras with base field the field of rationals. Construction A is a well studied method to obtain lattices from codes via quotient of different rings, such as rings of integers, in which case mostly cyclotomic number fields have been considered. In this thesis, we will study Construction A over all totally real and CM fields. Using Construction A, the intersection between a lattice constructed from a linear complementary dual (LCD) code and its dual lattice is investigated. This is an attempt to find an equivalent definition to LCD codes for lattices. Several new constructions of existing extremal lattices as well as a new extremal lattice are obtained from the above mentioned methods. The mathematical concepts used in this thesis mainly involve algebraic number theory, class field theory, non commutative algebra and coding theory. ​Doctor of Philosophy (SPMS)

We present an algorithmic strategy to compute an upper bound for the degree of the algebraic solutions of non-degenerate polynomial differential equations in dimension two.

Constructing algebraic polynomials using computer algebra techniques is believed to be state-of-the-art in analyzing gate-level arithmetic circuits. However, the existing approach applies algebraic rewriting directly to the gate-level netlist, which has potential memory explosion problem. This paper introduces an algebraic rewriting technique based on the and-inverter graph (AIG) representation of gate-level designs. Using AIG-based cut-enumeration and truth table computation, an efficient order of algebraic rewriting is identified, resulting in dramatic simplifications of the polynomial under construction. An automatic approach, which further reduces the complexity of algebraic rewriting by handling redundant polynomials, is also proposed.

In this note we prove the following surprising characterization: if X ⊂ is an (embedded, non-empty, proper) algebraic variety deûned over a field k of characteristic zero, then X is a hypersurface if and only if the module of logarithmic vector fields of X is a reflexive -module. As a consequence of this result, we derive that if is a free -module, which is shown to be equivalent to the freeness of the t-th exterior power of for some (in fact, any) t ≤ n, then necessarily X is a Saito free divisor.

We give positive characteristic analogues of complex entire functions having remarkable property that their values as well as their derivatives of any order at any nonzero algebraic numbers are algebraically independent. These results are obtained by establishing a criterion for the algebraic independence of the values of Mahler functions as well as that of the algebraic independence of the Mahler functions themselves over any function fields of positive characteristic.

This work is shown below, the algebraic sum of the two functions selected from class S of univalent functions which is a subclass of this class A of functions f(z) satisfy the conditions analiytic in the open unit disk U={z∈C:|z

Bu makalede proksimal relator uzaylarında yaklaşımlı yarıgruplar ve ideallere giriş yapılmıştır. Tanımsal proksimiti bağıntısı ile birlikte dikkate alınan dijital görüntülerde yaklaşımlı yarıgrup ve ideal örnekleri verilmiştir. Bundan başka, nesne tanımlaması homomorfizması kullanılarak tanımsal yaklaşımların bazı özellikleri incelenmiştir.

This work makes a contribution to algebraic parameter estimation as it proposes a simple alternative to the derivation of the algebraic estimation equations. The idea is based on a system representation in the form of an evaluation functional which does not exhibit any singularities in the neighbourhood of zero. Implied is the fact that algebraic estimation of parameters as well as system states can then truly be performed in arbitrary time and with uniform accuracy over the entire estimation interval. Additionally, the result offers a geometric representation of a linear system as a finite dimensional subspace of a Hilbert space, that readily suggests powerful noise rejection methods in which invariance plays a central role.

The division algorithm for ideals of algebraic power series satisfying Hironaka’s box condition is shown to be finite when expressed suitably in terms of the defining polynomial codes of the series. In particular, the codes of the reduced standard basis of the ideal can be constructed effectively.

We compare families of functions related to the Darboux property (functions having the 𝒜-Darboux property) with family of strong Świątkowski functions using the notions of strong c-algebrability. We also compare families of functions associated with density topologies.

J.R. Sendra is member of the Research Group ASYNACS (Ref.CT-CE2019/683), The resultant theory plays a crucial role in computational algebra and algebraic geometry. The theoryhas two aspects: algebraic and geometric. In this paper, we focus on the algebraic aspect. One of themost important and well known algebraic properties of the resultant is that it is equal to the determinantof the Sylvester matrix. In 2008, Odagiri proved that a similar property holds over the tropical semiringif one replaces subtraction with addition. The tropical semiring belongs to a large family of algebraicstructures called commutative idempotent semiring. In this paper, we prove that the same property(with subtraction replaced with addition) holds over an arbitrary commutative idempotent semiring., Ministerio de Economía y Competitividad

The foundation of algebraic geometry is the solving of systems of polynomial equations. When the equations to be considered are defined over a subfield of the complex numbers, numerical methods can be used to perform algebraic geometric computations forming the area of numerical algebraic geometry. This article provides a short introduction to numerical algebraic geometry with the subsequent articles in this special issue considering three current research topics: solving structured systems, certifying the results of numerical computations, and performing algebraic computations numerically via Macaulay dual spaces.

A smooth variety is called uniformly rational if every point admits a Zariski open neighborhood isomorphic to a Zariski open subset of the affine space. In this note we show that every smooth and rational affine variety endowed with an algebraic torus action such that the algebraic quotient has dimension 0 or 1 is uniformly rational., Comment: 4 pages

The solution set of a system of polynomial equations, called an algebraic set, can be decomposed into finitely many irreducible components. In numerical algebraic geometry, irreducible algebraic sets are represented by witness sets, whereas general algebraic sets allow a numerical irreducible decomposition comprising a collection of witness sets, one for each irreducible component. We denote the solution set of any system of polynomials f : C N ź C n as V ( f ) ź C N . Given a witness set for some algebraic set Z ź C N and a system of polynomials f : C N ź C n , the algorithms of this paper compute a numerical irreducible decomposition of the set Z ź V ( f ) . While extending the types of intersection problems that can be solved via numerical algebraic geometry, this approach is also a unification of two existing algorithms: the diagonal intersection algorithm and the homotopy membership test. The new approach includes as a special case the "extension problem" where one wishes to intersect an irreducible component A of V ( g ( x ) ) with V ( f ( x , y ) ) , where f introduces new variables, y. For example, this problem arises in computing the singularities of A when the singularity conditions are expressed in terms of new variables associated to the tangent space of A. Several examples are included to demonstrate the effectiveness of our approach applied in a variety of scenarios.

This paper gives conditions for algebraic independence of a collection of functions satisfying a certain kind of algebraic difference relations. As applications, we show algebraic independence of two collections of special functions: (1) Vigneras' multiple gamma functions and derivatives of the gamma function, (2) the logarithmic function, \(q\)-exponential functions and \(q\)-polylogarithm functions. In a similar way, we give a generalization of Ostrowski's theorem.

Differential algebraic geometry seeks to extend the results of its algebraic counterpart to objects defined by differential equations. Many notions, such as that of a projective algebraic variety, have close differential analogues but their behavior can vary in interesting ways. Workers in both differential algebra and model theory have investigated the property of completeness of differential varieties. After reviewing their results, we extend that work by proving several versions of a “differential valuative criterion" and using them to give new examples of complete differential varieties. We conclude by analyzing the first examples of incomplete, finite-rank projective differential varieties, demonstrating a clear difference from projective algebraic varieties.

A group action on the input ring or category induces an action on the algebraic $K$-theory spectrum. However, a shortcoming of this naive approach to equivariant algebraic $K$-theory is, for example, that the map of spectra with $G$-action induced by a $G$-map of $G$-rings is not equivariant. We define a version of equivariant algebraic $K$-theory which encodes a group action on the input in a functorial way to produce a $genuine$ algebraic $K$-theory $G$-spectrum for a finite group $G$. The main technical work lies in studying coherent actions on the input category. A payoff of our approach is that it builds a unifying framework for equivariant topological $K$-theory, Atiyah's Real $K$-theory, and existing statements about algebraic $K$-theory spectra with $G$-action. We recover the map from the Quillen-Lichtenbaum conjecture and the representational assembly map studied by Carlsson and interpret them from the perspective of equivariant stable homotopy theory., Comment: Final version to appear in Mathematische Zeitschrift. The last section about Waldhausen G-categories has been removed from this paper

Let P k : = F 2 [ x 1 , x 2 , … , x k ] be the graded polynomial algebra over the prime field of two elements F 2 , in k generators x 1 , x 2 , … , x k , each of degree 1. Being the mod-2 cohomology of the classifying space B ( Z / 2 ) k , the algebra P k is a module over the mod-2 Steenrod algebra A . In this Note, we extend a result of Hưng on Kameko's homomorphism S q ˜ ⁎ 0 : F 2 ⊗ A P k ⟶ F 2 ⊗ A P k . Using this result, we show that Singer's conjecture for the algebraic transfer is true in the case k = 5 and the degree 7.2 s − 5 with s an arbitrary positive integer.

Let $X$ be a connected affine homogenous space of a linear algebraic group $G$ over $\C$. (1) If $X$ is different from a line or a torus we show that the space of all algebraic vector fields on $X$ coincides with the Lie algebra generated by complete algebraic vector fields on $X$. (2) Suppose that $X$ has a $G$-invariant volume form $\omega$. We prove that the space of all divergence-free (with respect to $\omega$) algebraic vector fields on $X$ coincides with the Lie algebra generated by divergence-free complete algebraic vector fields on $X$ (including the cases when $X$ is a line or a torus). The proof of these results requires new criteria for algebraic (volume) density property based on so called module generating pairs., Comment: 21 pages

The goals of this paper fall into two closely related areas. First, we develop a formal framework for deterministic unital quantities in which measurement unitization is understood to be a built-in feature of quantities rather than a mere annotation of their numerical values with convenient units. We introduce this idea within the setting of certain ordered semigroups of physical-geometric states of classical physical systems. States are assumed to serve as truth makers of metrological statements about quantity values. A unital quantity is presented as an isomorphism from the target system’s ordered semigroup of states to that of positive reals. This framework allows us to include various derived and variable quantities, encountered in engineering and the natural sciences. For illustration and ease of presentation, we use the classical notions of length, time, electric current and mean velocity as primordial examples. The most important application of the resulting unital quantity calculus is in dimensional analysis. Second, in evaluating measurement uncertainty due to the analog-to-digital conversion of the measured quantity’s value into its measuring instrument’s pointer quantity value, we employ an ordered semigroup framework of pointer states. Pointer states encode the measuring instrument’s indiscernibility relation, manifested by not being able to distinguish the measured system’s topologically proximal states. Once again, we focus mainly on the measurement of length and electric current quantities as our motivating examples. Our approach to quantities and their measurement is strictly state-based and algebraic in flavor, rather than that of a representationalist-style structure-preserving numerical assignment.

Generalized hypergeometric differential equations of arbitrary order are considered. Necessary and sufficient conditions for the algebraic independence of solutions of collections of such equations, as well as of their values at algebraic points, are obtained.

New multivariable asymmetric public-key encryption schemes based on the NP-complete problem of simultaneous algebraic Riccati equations over finite fields are suggested. We also provide a systematic way to describe any set of quadratic equations over any field, as a set of algebraic Riccati equations. This has the benefit of systematic algebraic crypt-analyzing any encryption scheme based on quadratic equations, to any possible vulnerable hidden structure, in view of the fact that the set of all solutions to any given single algebraic Riccati equation is fully described in terms of all the T -invariant subspaces of some restricted dimension, where T is the matrix of coefficients of the related algebraic Riccati equation.

Under study is the component algebraic immunity of vectorial Boolean functions. We prove a theorem on the correspondence between the maximal component algebraic immunity of a function and its balancedness. Some relationship is obtained between the maximal component algebraic immunity and matrices of a special form. We construct several functions with maximal component algebraic immunity in case of few variables.

We use a geometric technique based on embeddings of graphs to provide an explicit formula for the absolute algebraic connectivity and its eigenvectors of double brooms. Besides, we give a polynomial time combinatorial algorithm that computes the absolute algebraic connectivity of a given tree.

For connected simple algebraic groups defined over an algebraically closed field of characteristic zero, the classifications of irreducible algebraic representations of modalities 0, 1, and 2 are obtained.

Here we discuss the intersection multiplicities of holomorphic and algebraic curves with divisors on an algebraic variety as an analogue to the abc-Conjecture. We announce some new results.

Following work on abstracting the concept of an algebra to that of an algebraic system and of an ordered algebra to that of an ordered algebraic system, the notion of a flrst-order structure is abstracted to obtain structure systems. The algebraic part of a structure system is an algebraic system rather than an algebra as is the case in the ordinary flrst-order structures. This abstraction is accompanied by the introduction of a suitably modifled notion of a countable flrst-order language with the aim of developing a flrst-order model theory of structure systems and, therefore, axiomatizing classes of structure systems. After introducing some basic constructions on structure systems, including the ultraproduct construction, an analog of ˆ

We give a concise introduction to the Farrell-Jones Conjecture in algebraic $K$-theory and to some of its applications. We survey the current status of the conjecture, and we illustrate the two main tools that are used to attack it: controlled algebra and trace methods.

We study the rational solutions of systems of first-order algebraic partial differential equations and relate them to those of an associated autonomous system. We also describe how rational general solutions of these systems are related, and provide an algorithm in some particular case concerning the dimension of the associated algebraic variety. Our results can be considered as a generalization of the approach by L. X. C. Ngô and F. Winkler on algebraic ordinary differential equations of order one, adapted to systems of first-order algebraic partial differential equations., Ministerio de Economía y Competitividad

This paper examines semiprime algebras A with a q -skew σ -derivation δ , where both δ and σ are algebraic. With minor assumptions on the ground field, we show that if the invariants A δ are algebraic of bounded degree, then A must be finite dimensional. As an application, it is shown that if A is a semiprime Banach algebra and δ is continuous, then whenever A δ is algebraic, it follows that A is finite dimensional.

This study aims at introducing new algebraic multi-level solution techniques for linear systems with M-matrices. Previous optimal geometric constructions by multi-level generating systems or multi-level frames are adapted. The new contribution is a purely algebraic construction of multi-level frames. A new class of algebraic multi-level algorithms is derived by applying subspace correction iterative solvers to the algebraic multi-level linear system. These algorithms feature error resilience properties and potential massive parallelism. The proposed work outperforms previous geometric constructions since a black-box, geometry-independent methodology is considered. Moreover, optimality results of geometric constructions are matched. Overall, the new method will be well suited for generic linear algebra libraries for future multi- and many-core systems.

The new notion of intrinsic algebraic entropy ent ˜ of endomorphisms of Abelian groups is introduced and investigated. The intrinsic algebraic entropy is compared with the algebraic entropy, a well-known numerical invariant introduced in the sixties and recently deeply studied also in its relations to other fields of Mathematics. In particular, it is shown that the intrinsic algebraic entropy and the algebraic entropy coincide on endomorphisms of torsion Abelian groups, and their precise relation is clarified in the torsion-free case. The Addition Theorem and the Uniqueness Theorem are also proved for ent ˜ , in analogy with similar results for the algebraic entropy. Furthermore, a relevant connection of ent ˜ to the algebraic entropy of a continuous endomorphism of a locally compact Abelian group G is pointed out; this allows for the computation of the algebraic entropy in case G is totally disconnected.

Let X be any locally analytic subset of C m . We show that for every a in X and for every natural number ν, there is an algebraic subset X ν of C m approximating X, in some neighborhood of a, such that the order of tangency of X and X ν at a is at least ν.

The algebraic approach to the analysis of system reliability associates an algebraic object, a monomial ideal, to a coherent system (CS), and studies the reliability of the system using the Hilbert series of the monomial ideal. New capabilities of the algebraic method in system design are shown, in particular related to enumeration of working states. The algebraic method should be a useful tool in reliability, both for performing different computations on system features, and to study the structure of systems.

Some results obtained in the paper “Algebraic connections on projective modules with prescribed curvature” rely on a PBW-theorem from 1963 which has turned out not to be true. In this note I explain this.

Multivariate residues appear in many different contexts in theoretical physics and algebraic geometry. In theoretical physics, they for example give the proper definition of generalized-unitarity cuts, and they play a central role in the Grassmannian formulation of the S-matrix by Arkani-Hamed et al. In realistic cases their evaluation can be non-trivial. In this paper we provide a Mathematica package for efficient evaluation of multidimensional residues based on methods from computational algebraic geometry. The package moreover contains an implementation of the global residue theorem, which produces relations between residues at finite locations and residues at infinity., 43 pages, 4 figures. Application to Cachazo-He-Yuan scattering equations added; journal version. The package MultivariateResidues can be downloaded from https://bitbucket.org/kjlarsen/multivariateresidues/raw/master/release/MultivariateResidues.zip

Lie–Butcher (LB) series are formal power series expressed in terms of trees and forests. On the geometric side LB-series generalizes classical B-series from Euclidean spaces to Lie groups and homogeneous manifolds. On the algebraic side, B-series are based on pre-Lie algebras and the Butcher-Connes-Kreimer Hopf algebra. The LB-series are instead based on post-Lie algebras and their enveloping algebras. Over the last decade the algebraic theory of LB-series has matured. The purpose of this paper is twofold. First, we aim at presenting the algebraic structures underlying LB series in a concise and self contained manner. Secondly, we review a number of algebraic operations on LB-series found in the literature, and reformulate these as recursive formulae. This is part of an ongoing effort to create an extensive software library for computations in LB-series and B-series in the programming language Haskell.

In this paper we characterize all cubic polynomial differential systems in the plane having two circles as invariant algebraic limit cycles. The first author is partially supported by a MINECO grant number MTM2014-53703-P, and an AGAUR (Generalitat de Catalunya) grant number 2014SGR 1204. The second author is partially supported by a MINECO grant MTM2013-40998-P, an AGAUR grant 2014SGR 568, and two grants FP7-PEOPLE-2012-IRSES numbers 316338 and 318999. The third author is partially supported by FCT/Portugal through the project UID/MAT/04459/2013.

Algebraic immunity is a cryptographic criterion for Boolean functions used in cryptosystem to resist algebraic attacks. They usually should have high algebraic immunity. Chen proposed a first order recursive construction of Boolean functions and checked that they had optimum algebraic immunity for n 0.