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In this paper I will discuss the fundamental ideas behind proof assistants: What are they and what is a proof anyway? I give a short history of the main ideas, emphasizing the way they ensure the correctness of the mathematics formalized. I will also briefly discuss the places where proof assistants are used and how we envision their extended use in the future. While being an introduction into the world of proof assistants and the main issues behind them, this paper is also a position paper that pushes the further use of proof assistants. We believe that these systems will become the future of mathematics, where definitions, statements, computations and proofs are all available in a computerized form. An important application is and will be in computer supported modelling and verification of systems. But there is still a long road ahead and I will indicate what we believe is needed for the further proliferation of proof assistants. [ABSTRACT FROM AUTHOR]

Two letters from William Burnside have recently been found in the Nachlass of Robert Fricke that contain instances of the Burnside Problem prior to its first publication. We present these letters as a whole to the public for the first time. We draw a picture of these two mathematicians and describe their activities leading to their correspondence. We thus gain an insight into their respective motivations, reactions, and attitudes, which may sharpen the current understanding of professional and social interactions of the mathematical community at the turn of the twentieth century. [ABSTRACT FROM AUTHOR]

The discoveries of Herculaneum and Pompeii and the broadened scope of geography in the eighteenth century, and developments in mathematics and physics that began in the nineteenth and continued into the twentieth, renewed studies of ancient works of art led to the creation of opposing factions regarding the "question of perspective": those who maintained the existence of a single possible perspective, and those who upheld the existence of multiple perspective constructions. To shed light on the debate, this present paper examines some of the factors behind the two positions. [ABSTRACT FROM AUTHOR]

In this paper, we extend the asymptotic analysis in (Licht et al. in J. Math. Pures Appl. 99:685–703, 2013) performed, in the framework of small strains, on a structure consisting of two linearly elastic bodies connected by a thin soft nonlinear Kelvin–Voigt viscoelastic adhesive layer to the case in which the total mass of the layer remains strictly positive as its thickness tends to zero. We obtain convergence results by means of a nonlinear version of Trotter's theory of approximation of semigroups acting on variable Hilbert spaces. Differently from the limit models derived in (Licht et al. in J. Math. Pures Appl. 99:685–703, 2013), in the present analysis the dynamic effects on the surface to which the layer shrinks do not disappear. Thus, the limiting behavior of the remaining bodies is described not only in terms of their displacements on the contact surface, but also by an additional variable that keeps track of the dynamics in the adhesive layer. [ABSTRACT FROM AUTHOR]

The paper deals with the study of the existence result for a Kirchhoff elliptic system with additive right-hand side and variable parameters by using the sub-/supersolution method. Our study is a natural extension result of our previous one in (Boulaaras and Guefaifia in Math. Methods Appl. Sci. 41:5203–5210, 2018), where we discussed only the simple case when the parameters are constant. [ABSTRACT FROM AUTHOR]

In this paper, we propose a Dai–Liao (DL) conjugate gradient method for solving large-scale system of nonlinear equations. The method incorporates an extended secant equation developed from modified secant equations proposed by Zhang et al. (J Optim Theory Appl 102(1):147–157, 1999) and Wei et al. (Appl Math Comput 175(2):1156–1188, 2006) in the DL approach. It is shown that the proposed scheme satisfies the sufficient descent condition. The global convergence of the method is established under mild conditions, and computational experiments on some benchmark test problems show that the method is efficient and robust. [ABSTRACT FROM AUTHOR]

In this paper, we proved two new Riemann–Liouville fractional Hermite–Hadamard type inequalities for harmonically convex functions using the left and right fractional integrals independently. Also, we have two new Riemann–Liouville fractional trapezoidal type identities for differentiable functions. Using these identities, we obtained some new trapezoidal type inequalities for harmonically convex functions. Our results generalize the results given by İşcan (Hacet J Math Stat 46(6):935–942, 2014). [ABSTRACT FROM AUTHOR]

This paper is concerned with the number of limit cycles bifurcating from a period annulus for some planar piecewise smooth non-Hamiltonian systems. We construct a planar piecewise quadratic system with multiple parameters, obtain its lower bound for the maximum number of limit cycles by using Melnikov function method, and find more limit cycles than (Li and Liu in J. Math. Anal. Appl. 428:1354–1367, 2015). [ABSTRACT FROM AUTHOR]

In this paper, we study the following Choquard type quasilinear Schrödinger equation: − Δ u + u − Δ (u 2) u = (I α ∗ G (u)) g (u) , x ∈ R N , where N ≥ 3 , 0 < α < N , and I α is a Riesz potential. By using the minimization method developed by (Tang and Chen in Adv. Nonlinear Anal. 9:413–437, 2020; Willem in Minimax Theorems, 1996), we establish the existence of ground state solutions with general Choquard type nonlinearity. Our results extend the results obtained by (Chen et al. in Appl. Math. Lett. 102:106141, 2020). [ABSTRACT FROM AUTHOR]

Recently, Wu (Mathematics 6(11):219, 2018; Mathematics 6(6):90, 2018) introduced the concept of a near-fixed point and established some results on near fixed points in a metric interval space and hyperspace. Motivated by these papers, we studied the near-coincidence point theorem in these spaces via a simulation function. To show the authenticity of the established results and definitions, we also provide some examples. [ABSTRACT FROM AUTHOR]

The interview has been reproduced with permission from Bhāvanā: The mathematics magazine, A publication of the Bhavana Trust, Volume 2, Issue 4, October 2018. http://bhavana.org.in/ms-narasimhan/ [ABSTRACT FROM AUTHOR]

Two nonlinear feedback shift registers (NFSRs) of the same stage number are called isomorphic if their state diagrams are of the same cycle structure. In this paper, we focus on a class of isomorphic NFSRs that are derived from a previous work (Zhao et al. in Des Codes Cryptogr 86(12):2775–2790, 2018). First, we give an explicit formula for counting this class of isomorphic NFSRs, which generalizes the previous result given by Rozhkov (Discret Math Appl 20(2):127–155, 2010). Then we study the inherent relation of the affine sub-families among these NFSRs. The obtained result shows that the analysis of the affine sub-families of these NFSRs could be reduced to the analysis of the affine sub-families of a specific NFSR. Finally, we present a Galois representation of some specific isomorphic NFSRs whose periods of the output sequences are controllable. [ABSTRACT FROM AUTHOR]

In this paper, we use a new powerful technique of arbitrary-order fractional (AOF) characteristic method (CM) to solve the AOF hyperbolic nonlinear scalar conservation law (HNSCL) of time and space. We present the existence and uniqueness of this class of equations in time and one-dimensional space of fractional arbitrary order. We extend Jumarie's modification of Riemann–Liouville and Caputo's definition of the fractional arbitrary order to introduce some formulae (Appl. Math. Lett. 22:378–385, 2009; Appl. Math. Lett. 18:739–748, 2005). Then, we use these formulae to prove the main theorem. In the application section, we use the analytical technique that is presented in the theorem to solve examples that are given. [ABSTRACT FROM AUTHOR]

During this digital era, France, like many other countries, is undergoing a transition from paper-based assessments to digital assessments in education. There is a rising interest in technology-enhanced items which offer innovative ways to assess traditional competencies, as well as addressing problem solving skills, specifically in mathematics. The rich log data captured by these items allows insight into how students approach the problem and their process strategies. Educational data mining is an emerging discipline developing methods suited for exploring the unique and increasingly large-scale data that come from such settings. Data-driven methods can be helpful when trying to make sense of process data. However, studies have shown that didactically meaningful findings are most likely generated when data mining techniques are guided by theoretical principles on subjects' skills. In this study, theoretical didactical grounding has been essential for developing and describing interactive mathematical tasks as well as defining and identifying strategic behaviors from the log data. Interactive instruments from France's national large-scale assessment in mathematics have been pilot tested in May 2017. Feature engineering and classical machine learning analysis were then applied to the process data of one specific technology-enhanced item. Supervised learning was implemented to determine the model's predictive power of students' achievement and estimate the weight of the variables in the prediction. Unsupervised learning aimed at clustering the samples. The obtained clusters are interpreted by the mean values of the important features. Both the analytical model and the clusters enable us to identify among students two conceptual approaches that can be interpreted in theoretically meaningful ways. If there are limitations to relying on log data analysis in order to determine learning profiles, one of them is the fact that this information remains partial when it comes to describing the complete cognitive activity at play, the potential of technology-enriched problem solving situations in large-scale assessments is nevertheless obvious. The type of findings this study produced is actionable from teachers' perspective in order to address students' specific needs. [ABSTRACT FROM AUTHOR]

Işık et al. (Mathematics 7:862, 2019) presented an interesting generalization of the Banach contraction principle. In this paper, motivated by Işık et al., we give a new extension of the well-known Darbo inequality in a Banach space. Our results provide several generalizations of the Darbo inequality. As an application, we study the existence of solutions for a system of functional integral equations in C [ 0 , T ] . Finally, we expose a genuine example to support the effectiveness of our results. [ABSTRACT FROM AUTHOR]

This paper is devoted to the uniqueness of q-difference-differential polynomials of different types. Using the idea of common zeros and common poles (Chin. Ann. Math., Ser. A 35:675–684, 2014), we improve the conditions of the former theorems and obtain some new results on the uniqueness of q-difference-differential polynomials of meromorphic functions. [ABSTRACT FROM AUTHOR]

In this paper, the 3-rank of the incidence matrices of 2-designs supported by the minimum weight codewords in a family of ternary linear codes considered in Ding and Li (Discret Math 340(10):2415–2431, 2017) are computed. A lower bound on the minimum distance of the ternary codes spanned by the incidence matrices of these designs is derived, and it is proved that the codes are subcodes of the 4th order generalized Reed–Muller codes. [ABSTRACT FROM AUTHOR]

In this paper, finite time blow-up property of solutions to a p-Kirchhoff-type parabolic equation with general nonlinearity is considered. Some sufficient conditions are given for the weak solutions to blow up in finite time. An upper bound for the blow-up time is also derived. The results partially generalize some recent ones reported by Han and Li (Comput Math Appl. 2018;75:3283–3297). [ABSTRACT FROM AUTHOR]

In this paper, we introduce a new scheme based on the exponential spline function for solving linear second-order Fredholm integro-differential equations. Our approach consists of reducing the problem to a set of linear equations. We prove the convergence analysis of the method applied to the solution of integro-differential equations. The method is described and illustrated with numerical examples. The results reveal that the method is accurate and easy to apply. Moreover, results are compared with the method in (J. Comput. Appl. Math. 290:633–640, 2015). [ABSTRACT FROM AUTHOR]

Optimization Modulo Theories (OMT ) is an extension of SMT which allows for finding models that optimize given objectives. OptiMathSAT is an OMT solver which allows for solving a list of optimization problems on SMT formulas with linear objective functions—on the Boolean, the rational and the integer domains, and on their combination thereof—including (partial weighted) MaxSMT. Multiple and heterogeneous objective functions can be combined together and handled either independently, or lexicographically, or in linear or min–max /max–min combinations. OptiMathSAT provides an incremental interface, it supports both an extended version of the SMT-LIBv2 language and a subset of the FlatZinc language, and can be interfaced via an API. In this paper we describe OptiMathSAT and its usage in full detail. [ABSTRACT FROM AUTHOR]

In this paper we describe the implementation of , a resolution-based prover for the basic multimodal logic K n . The prover implements a resolution-based calculus for both local and global reasoning. The user can choose different normal forms, refinements of the basic resolution calculus, and strategies. We describe these options in detail and discuss their implications. We provide experiments comparing some of these options and comparing the prover with other provers for this logic. [ABSTRACT FROM AUTHOR]

The paper discusses a generic procedure for the parameter design of product and process development using planned and non-planned experiments. The method can predict the system sensitivity (robustness) against the stochastic stressful noises (e.g., unit-to-unit, stochastic chocks, environmental variation) and the non-natural sources of variation explaining the inability of the developed product/process to achieve its optimal functionality, beyond the pure random disturbances. The intrinsic and the extrinsic insensitivity components are isolated and evaluated using the stochastic frontier production methodology. The Cobb-Douglas and the TransLog, two accepted functional forms for the stochastic frontier model, are used to check the sample data adequacy and predictability. Hypothesis tests regarding the magnitude and the direction of the intrinsic and the extrinsic robustness components, the distributional form of the extrinsic insensitivity, and the estimation of the stochastic frontier parameters are performed using the maximum likelihood estimator. Finally, for the sake of completeness and applicability, the method has been demonstrated using three industrial case studies. [ABSTRACT FROM AUTHOR]

Motivated by the expressive power of completely positive programming to encode hard optimization problems, many approximation schemes for the completely positive cone have been proposed and successfully used. Most schemes are based on outer approximations, with the only inner approximations available being a linear programming based method proposed by Bundfuss and Dür (SIAM J Optim 20(1):30–53, 2009) and also Yıldırım (Optim Methods Softw 27(1):155–173, 2012), and a semidefinite programming based method proposed by Lasserre (Math Program 144(1):265–276, 2014). In this paper, we propose the use of the cone of nonnegative scaled diagonally dominant matrices as a natural inner approximation to the completely positive cone. Using projections of this cone we derive new graph-based second-order cone approximation schemes for completely positive programming, leading to both uniform and problem-dependent hierarchies. This offers a compromise between the expressive power of semidefinite programming and the speed of linear programming based approaches. Numerical results on random problems, standard quadratic programs and the stable set problem are presented to illustrate the effectiveness of our approach. [ABSTRACT FROM AUTHOR]

Simulation and verification of numerically controlled (NC) manufacturing processes require efficient visualization and analysis of the swept volume generated by the motion of freeform NC tools along complex 3D paths. State-of-the-art methods are either based on approximation techniques (thus lacking the level of accuracy required in NC manufacturing) or are based on analytical solutions with high computational complexity, which are not suitable for real-time applications. In addition, until recently, modeling the self-intersection of a generated volume was thought to be obstructed by seemingly complex mathematics. This paper proposes solving the sweeping problem by using the sweep-envelope differential equation (SEDE). This method has advantages over other methods in terms of low computational complexity and high accuracy. Moreover, this method includes efficient tools for self-intersection detection and modeling. In this paper, we present an enhanced self-intersection algorithm and apply the SEDE algorithm on a ball-end cutter that is swept along non-intersecting and self-intersecting cutter paths. [ABSTRACT FROM AUTHOR]

In this paper, I review both mathematics education and CSCL literature and discuss how we can better take advantage of CSCL tools for developing mathematical proof skills. I introduce a model of proof in school mathematics that incorporates both empirical and deductive ways of knowing. I argue that two major forces have given rise to this conception of proving: a particular learning perspective promoted in reform documents and a genre of computer tools, namely dynamic geometry software, which affords this perspective of learning within the context of mathematical proof. Tracing the move from absolutism to fallibilism in the philosophy of mathematics, I highlight the vital role of community in the production of mathematical knowledge. This leads me to an examination of a certain CSCL tool whose design is guided by knowledge-building pedagogy. I argue that knowledge building is a suitable pedagogical approach for the proof model presented in this paper. Furthermore, I suggest software modifications that will better support learners’ participation in authentic proof tasks. [ABSTRACT FROM AUTHOR]

Abstract  This paper compares the statement ‘Mathematics is the study of structure’ with the actual practice of mathematics. We present two examples from contemporary mathematical practice where the notion of structure plays different roles. In the first case a structure is defined over a certain set. It is argued firstly that this set may not be regarded as a structure and secondly that what is important to mathematical practice is the relation that exists between the structure and the set. In the second case, from algebraic topology, one point is that an object can be a place in different structures. Which structure one chooses to place the object in depends on what one wishes to do with it. Overall the paper argues that mathematics certainly deals with structures, but that structures may not be all there is to mathematics. [ABSTRACT FROM AUTHOR]

Abstract  The paper describes a systematic computational study of the prime counting function π(x) and three of its analytic approximations: the logarithmic integral , , and , where μ is the Möbius function. The results show that π(x)x) for 2≤x≤1014, and also seem to support several conjectures on the maximal and average errors of the three approximations, most importantly and for all x>2. The paper concludes with a short discussion of prospects for further computational progress. [ABSTRACT FROM AUTHOR]

Scientific anomalies are observations and facts that contradict current scientific theories and they are instrumental in scientific theory change. Philosophers of science have approached scientific theory change from different perspectives as Darden (Theory change in science: Strategies from Mendelian genetics, 1991) observes: Lakatos (In: Lakatos, Musgrave (eds) Criticism and the growth of knowledge, 1970) approaches it as a progressive “research programmes” consisting of incremental improvements (“monster barring” in Lakatos, Proofs and refutations: The logic of mathematical discovery, 1976), Kuhn (The structure of scientific revolutions, 1996) observes that changes in “paradigms” are instigated by a crisis from some anomaly, and Hanson (In: Feigl, Maxwell (eds) Current issues in the philosophy of science, 1961) proposes that discovery does not begin with hypothesis but with some “problematic phenomena requiring explanation”. Even though anomalies are important in all of these approaches to scientific theory change, there have been only few investigations into the specific role anomalies play in scientific theory change. Furthermore, much of these approaches focus on the theories themselves and not on how the scientists and their experiments bring about scientific change (Gooding, Experiment and the making of meaning: Human agency in scientific observation and experiment, 1990). To address these issues, this paper approaches scientific anomaly resolution from a meaning construction point of view. Conceptual integration theory (Fauconnier and Turner, Cogn Sci 22:133–187, 1996; The way we think: Conceptual blending and mind’s hidden complexities, 2002) from cognitive linguistics describes how one constructs meaning from various stimuli, such as text and diagrams, through conceptual integration or blending. The conceptual integration networks that describe the conceptual integration process characterize cognition that occurs unconsciously during meaning construction. These same networks are used to describe some of the cognition while resolving an anomaly in molecular genetics called RNA interference (RNAi) in a case study. The RNAi case study is a cognitive-historical reconstruction (Nersessian, In: Giere (ed) Cognitive models of science, 1992) that reconstructs how the RNAi anomaly was resolved. This reconstruction traces four relevant molecular genetics publications in describing the cognition necessary in accounting for how RNAi was resolved through strategies (Darden 1991), abductive reasoning (Peirce, In: Hartshorne, Weiss (eds) Collected papers, 1958), and experimental reasoning (Gooding 1990). The results of the case study show that experiments play a crucial role in formulating an explanation of the RNAi anomaly and the integration networks describe the experiments’ role. Furthermore, these results suggest that RNAi anomaly resolution is embodied. It is embodied in a sense that cognition described in the cognitive-historical reconstruction is experientially based. [ABSTRACT FROM AUTHOR]

This paper presents quantitative methods that allow scientists to compare the patterns in two maps that show a shared real variable. Specifically, this paper shows how to budget various components of agreement and disagreement between maps. The components are based on the separation of a map’s information of quantity from its information of location. The technique also examines how variation in resolution influences the measurement of the components of information. The manner in which the measurements change as a function of spatial resolution can be more important and interesting than the results at any single particular resolution, because the results at a single particular resolution may indicate more about the format of the data than about the overall pattern in the landscape. An example illustrates the mathematical concepts, and an application compares mapped vegetation indices in Africa to illustrate the usefulness of the proposed approach vis-à-vis a conventional approach. The results are presented visually in the form of stacked bar graphs that show separable components of information. The entire analysis is performed twice, each time with a different mathematical measurement of deviation: (1) root mean square error, and (2) mean absolute error. This paper compares these two approaches and discusses their relative advantages and disadvantages. Hopefully, this approach of budgeting components of information at multiple resolutions will become adopted as standard practice in the measurement of patterns. [ABSTRACT FROM AUTHOR]

The rise of the field of “experimental mathematics” poses an apparent challenge to traditional philosophical accounts of mathematics as an a priori, non-empirical endeavor. This paper surveys different attempts to characterize experimental mathematics. One suggestion is that experimental mathematics makes essential use of electronic computers. A second suggestion is that experimental mathematics involves support being gathered for an hypothesis which is inductive rather than deductive. Each of these options turns out to be inadequate, and instead a third suggestion is considered according to which experimental mathematics involves calculating instances of some general hypothesis. The paper concludes with the examination of some philosophical implications of this characterization. [ABSTRACT FROM AUTHOR]

This paper is devoted to the study of boundary value problem of third order functional differential equations. We obtain some existence results for the problem at resonance under the condition that the nonlinear terms is bounded or generally unbounded. In this paper we mainly use the topological degree theory. [ABSTRACT FROM AUTHOR]

This paper assesses the predictive accuracy of various analytical models and one numerical model (a CART-ANFIS network) of springback that are available with the existing literature using the mean square error and its decomposition into systematic and random components as a comparative measure of predictive accuracy. The numerical model was found to have no systematic bias in the springback predictions made, whilst for the analytical models the systematic bias accounted for about 11% of the mean square error. The CART-ANFIS network also had the smallest MSE and the prediction errors made were all random in nature. The paper ends by giving some illustrations of the CART-ANFIS numerical model in finding the proper die contour to correct for springback so as to achieve right first-time manufacturing for a wide range of sheet steels. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the stability of the solutions of a viscoelastic plate equation with a logarithmic nonlinearity. We assume that the relaxation function g satisfies the minimal condition g ′ (t) ≤ − ξ (t) G (g (t)) , where ξ and G satisfy some properties. With this very general assumption on the behavior of g, we establish explicit and general energy decay results from which we can recover the exponential and polynomial rates when G (s) = s p and p covers the full admissible range [ 1 , 2) . Our new results substantially improve and generalize several earlier related results in the literature such as Gorka (Acta Phys. Pol. 40:59–66, 2009), Hiramatsu et al. (J. Cosmol. Astropart. Phys. 2010(06):008, 2010), Han and Wang (Acta Appl. Math. 110(1):195–207, 2010), Messaoudi and Al-Khulaifi (Appl. Math. Lett. 66:16–22, 2017), Mustafa (Math. Methods Appl. Sci. 41(1):192–204, 2018), and Al-Gharabli et al. (Commun. Pure Appl. Anal. 18(1):159–180, 2019). [ABSTRACT FROM AUTHOR]

This paper obtains the weak completeness and decidability results for standard systems of modal logic using models built from formulas themselves. This line of work began with Fine (Notre Dame J. Form. Log. 16:229–237, 1975). There are two ways in which our work advances on that paper: First, the definition of our models is mainly based on the relation Kozen and Parikh used in their proof of the completeness of PDL, see (Theor. Comp. Sci. 113–118, 1981). The point is to develop a general model-construction method based on this definition. We do this and thereby obtain the completeness of most of the standard modal systems, and in addition apply the method to some other systems of interest. None of the results use filtration, but in our final section we explore the connection. [ABSTRACT FROM AUTHOR]

This paper deals with multicriteria discrete-continuous problems of scheduling nonpreemptable jobs. The need for reusability and modularity leads us to build a “generic” optimisation and simulation framework, while the need to quickly generate good compromises between conflicting objectives requires the implementation of multicriteria scheduling models. This paper describes the practical possibilities of three hybrid models within this framework. The validation of the framework is presented in terms of its application to a real, highly constrained, discrete-continuous problem. The optimisation model is based on the hybridisation of a classical hill-climber meta-heuristic with the Promethee II multicriteria method. [ABSTRACT FROM AUTHOR]

The basic assumption of this paper is that mathematics and history of mathematics are both forms of knowledge and, therefore, represent different ways of knowing. This was also the basic assumption of Fried (2001) who maintained that these ways of knowing imply different conceptual and methodological commitments, which, in turn, lead to a conflict between the commitments of mathematics education and history of mathematics. But that conclusion was far too peremptory. The present paper, by contrast, takes the position, relying in part on Saussurean semiotics, that the historian's and working mathematician's ways of knowing are complementary. Recognizing this fact, it is argued, brings us to a deeper understanding of ourselves as creatures that do mathematics. This understanding, which is a kind of mathematical self-knowledge, is then proposed as an alternative commitment for mathematics education. In light of that commitment, history of mathematics assumes an essential role in mathematics education both as a subject and as a mediator between the aforementioned ways of knowing. [ABSTRACT FROM AUTHOR]

Abstract??The paper considers the problem of finding a spanning arborescence on a directed network whose arc costs are partially known. It is assumed that each arc cost can take on values from a known interval defining a possible economic scenario. In this context, the problem of finding the spanning arborescence whichbetterapproaches to that of minimum overall cost under each possible scenario is studied. The minimax regret criterion is proposed in order to obtain such a robust solution of the problem. As it is shown, the bounds on the optimal value of the minimax regret optimization problem obtained in a previous paper, can be used here in a Branch and Bound algorithm in order to give an optimal solution. The computational behavior of the algorithm is tested through numerical experiments. [ABSTRACT FROM AUTHOR]

Abstract?? In this paper, we discuss distance measures for a number of different combinatorial optimization problems of which the solutions are best represented as permutations of items, sometimes composed of several permutation (sub)sets. The problems discussed include single-machine and multiple-machine scheduling problems, the traveling salesman problem, vehicle routing problems, and many others. Each of these problems requires a different distance measure that takes the specific properties of the representation into account. The distance measures discussed in this paper are based on a general distance measure for string comparison called the edit distance. We introduce several extensions to the simple edit distance, that can be used when a solution cannot be represented as a simple permutation, and develop algorithms to calculate them efficiently. [ABSTRACT FROM AUTHOR]

Abstract??Viscoplastic models including a saturation stress are considered. The existence of the saturation stress significantly changes the mathematical structure of solutions near maximum friction surfaces (surfaces where the friction stress is equal to the local shear yield stress). The main features of solutions based on such theories are: (a) sliding must occur at the maximum friction surfaces under certain conditions, (b) the velocity field may be singular in the vicinity of maximum friction surfaces. The objective of the present paper is to study these features of solutions. The mathematical structure obtained is considered to be advantageous for a class of materials and may lead to a convergence of viscoplastic solutions to the corresponding rigid perfectly plastic solutions. It seems that the latter is of importance for the construction of a unified theory that could describe the material behavior in the range from rate-independent plasticity to viscoplasticity. In the present paper, the study of the main features of the model is based on the exact closed-form solution to the problem of flow between two coaxial rotating cylinders. In the case of sliding, in addition to the aforementioned features, the asymptotic behavior of the velocity field in the vicinity of the maximum friction surface is found for a class of constitutive laws. [ABSTRACT FROM AUTHOR]

This paper presents a new theoretical result concerning Hoare Logic. It is shown here that the verification conditions that support a Hoare Logic program derivation are themselves sufficient to construct a correct implementation of the given pre-, and post-condition specification. This property is mainly of theoretical interest, though it is possible that it may have some practical use, for example if predicative programming methodology is adopted. The result is shown to hold for both the original, partial correctness, Hoare logic, and also a variant for total correctness derivations. [ABSTRACT FROM AUTHOR]

The paper focuses on the right and left eigenvectors of a network matrix that belong to the largest eigenvalue. It is shown that each of vector entries measures the walk centrality of the corresponding node’s position in the network’s link structure and of the positions of the node’s adjacent nodes; as a result, it indicates to which degree the node can be associated with the structure’s core, i.e., the structural coreness of the node. The relationship between the vectors’ coordinates and the position of the nodes, as well as the actual computation of the coordinates, is based on an iterative computational scheme known as the power method. The paper studies the method’s convergence for networks of different structure. Some possible applications are discussed. The paper also includes a numerical example dealing with a real network of 197 nodes and 780 links. [ABSTRACT FROM AUTHOR]

The framework for this paper is a recently developed theory of abstraction in context. The paper reports on data collected from one student working on tasks concerned with absolute value functions. It examines the relationship between mathematical constructions and abstractions. It argues that an abstraction is a consolidated construction that can be used to create new constructions. Newly formed constructions are fragile entities. In the course of consolidating a construction this student creates connections between the new construction and already established mathematical knowledge and develops a language to describe and guide mathematical actions related to the construction. The resulting abstraction is a more resilient form of the construction and the student is able to justify his assertions. The paper also examines issues in designing tasks to consolidate a construction. [ABSTRACT FROM AUTHOR]

Symbolic model checkers use BDDs to represent arithmetic constraints over bounded integer variables. The size of such BDDs can in the worst case be exponential in the number and size (in bits) of the integer variables. In this paper we show how to construct linear-sized BDDs for linear integer arithmetic constraints. We present basic constructions for atomic equality and inequality constraints and generalize our complexity results for arbitrary linear arithmetic formulas. We also present three alternative ways of handling out-of-bounds transitions and discuss heterogeneous bounds on integer variables. We experimentally compare our approach to other BDD-based symbolic model checkers and demonstrate that the algorithms presented in this paper can be used to improve their performance significantly. [ABSTRACT FROM AUTHOR]

In this paper, we prove Brennan's conjecture for conformal mappings f of the disk { z : | z| < 1} assuming that the Taylor coefficients of the function log( zf′( z)/ f( z)) at zero are nonnegative. We also obtain inequalities for the integral means over the circle | z| = r of the squared modulus of the function zf′( z)/ f( z). [ABSTRACT FROM AUTHOR]

The standard neoclassical growth model with quasi-geometric discounting is shown elsewhere (Krusell, P. and Smith, A., CEPR Discussion Paper No. 2651, 2000) to have multiple solutions. As a result, value-iterative methods fail to converge. The set of equilibria is however reduced if we restrict our attention to the interior (satisfying the Euler equation) solution. We study the performance of a grid-based Euler-equation methods in the given context. We find that such a method converges to an interior solution in a wide range of parameter values, not only in the “test” model with the closed-form solution but also in more general settings, including those with uncertainty. [ABSTRACT FROM AUTHOR]

In the present paper, we prove a fixed-point theorem for completely continuous multivalued mappings defined on a bounded convex closed subset X of the Hilbert space H which satisfies the tangential condition $$F(x) \cap (x + T_X (x)) \ne \emptyset$$ , where T X( x) is the cone tangent to the set X at a point x. The proof of this theorem is based on the method of single-valued approximations to multivalued mappings. In this paper, we consider a simple approach for constructing single-valued approximations to multivalued mappings. This approach allows us not only to simplify the proofs of already-known theorems, but also to obtain new statements needed to prove the main theorem in this paper. [ABSTRACT FROM AUTHOR]

The article reports that the Turan problem was stated by mathematician P. Turán in 1970 in connection with possible applications in the number theory. Further progress in the Turán problem was made in the papers of mathematicians D.V. Gorbachev and A.S. Manoshina. They've proved the Popov's conjecture and reduced the Turán problem for a rational "h" to a finite dimensional external problem and evaluated the result for it. In this article the Turán problem is solved for all rational "h" by considering several linear programming problems.

The aim of this paper is to examine the work of Tschirnhaus, La Hire and Leibniz on the theory of caustics, a subject whose history is closely linked to geometrical optics. The curves in question were examined by the most eminent mathematicians of the 17th century such as Huygens, Barrow and Newton and were subsequently studied analytically from the time of Tschirnhaus until the 19th century.Leibniz was interested in caustics and the subject probably inspired him in his discovery of the concept of envelopes of lines. [ABSTRACT FROM AUTHOR]

This paper presents an innovative approach to introducing pre-service early childhood teachers to math, science and technology education. The approach involves the creation of partnerships between pre-service early childhood and engineering students to conceive, develop, implement and evaluate curriculum in the area of math, science and technology by using robotics and the engineering design process. In this paper we first present the theoretical framework for the creation of these partnerships. We then introduce an experience done at Tufts University in which three different forms of partnership models evolved: the collaborator’s model, the external consultant’s model and the developer’s model. We also present different case studies from this experience and finally we conclude with some remarks and observations for making this work scalable and sustainable in other settings and universities. [ABSTRACT FROM AUTHOR]

In this paper, we study the behavior of solutions of a semilinear elliptic equation in the exterior of a compact set as $|x|\backslash to\; \backslash nomathbreak\; \backslash infty$. Such equations were considered by many authors (for example, Kondrat'ev, Landis, Oleinik, Veron, etc.). In the present paper, we study the case in which in the equation contains lower terms. The coefficients of the lower terms are arbitrary bounded measurable functions. It is shown that the solutions of the equation tend to zero as $|x|\backslash to\; \backslash nomathbreak\; \backslash infty$. [ABSTRACT FROM AUTHOR]