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In this paper we resolve a conjecture of Kresch and Tamvakis [Duke Math. J. 110 (2001), pp. 359–376]. Our result is the following. Theorem : For any positive integer D and any integers i,j (0\leq i,j \leq D), \; the absolute value of the following hypergeometric series is at most 1: \begin{equation*} {_4F_3} \left [ \begin {array}{c} -i, \; i+1, \; -j, \; j+1 \\ 1, \; D+2, \; -D \end{array} ; 1 \right ]. \end{equation*} To prove this theorem, we use the Biedenharn-Elliott identity, the theory of Leonard pairs, and the Perron-Frobenius theorem. [ABSTRACT FROM AUTHOR]

Inequalities are frequently used in various fields of mathematics to prove theorems. The existence of inequalities contributes significantly to the foundations of such branches. In this paper, we study the properties of order relations in the system of dual numbers, which is inspired by order relations defined on real numbers. Besides, some special inequalities that are used in various fields of mathematics, such as Cauchy-Schwarz, Minkowski, and Chebyshev are studied in this framework. An example is also provided to validate our research findings. [ABSTRACT FROM AUTHOR]

Students often experience cognitive conflicts when trying to interpret negative numbers' order and values because they do not correspond to their prior whole number knowledge. One way to trigger students' cognitive conflicts and support their conflict resolution meaningfully is through stories. Thus, I used a temperature-related mathematics storybook—Temperature Turmoil—to highlight the cognitive conflict students often experience because of relying on the integers' absolute value and introduce conflict resolution (i.e., integers have both absolute value and directed value). By incorporating interactive features, I used a multiple-case approach to describe three fifth graders' cognitive conflict and conflict resolution experiences. Harry, Lola, and Claire were engaged in control, interactive language, and interactive visual version of the storybook, respectively. I analyzed their responses to integer order and value questions on the pretest, session tests, and posttest as well as retellings to characterize the extent of their conflict and conflict resolution. All three benefited from the storybook with Lola making the most growth and using the mathematical language in her retellings more often. Harry, more accurately than others, described the mathematical ideas of the storybook in his retellings. Claire did not make large progress because of misinterpreting the language used in the integer values questions. This paper provides implications for how to make use of students' common conflicts to facilitate their learning, which adds to the current understanding of using cognitive conflict as a teaching strategy. Further, the findings contribute to underdeveloped research on the benefits and limitations of interactive mathematics storybooks. [ABSTRACT FROM AUTHOR]

This paper investigates the bifurcations of the following difference equations xn+1=axn+byne−xn,yn+1=cyn+dxne−yn,xn+1=ayn+bxne−yn,yn+1=cxn+dyne−xn,where a,b,c, and d are positive constants and the initial conditions x0 and y0 are positive numbers. Psarros, Papaschinopoulos, and Schinas (Math. Methods Appl. Sci., 2016, 39: 5216–5222) presented the semistability of the fixed point (0,0) when one eigenvalue is equal to 1 and the other eigenvalue has absolute value less than 1. In this paper, we consider another case: one eigenvalue is equal to −1. With the aid of the center manifold reduction theorem, we rigorously show that these two systems undergo flip bifurcations or generalized flip bifurcations. Moreover, the stability of the fixed point (0,0) and the existence of period‐two cycles are also given. [ABSTRACT FROM AUTHOR]

In this paper, based on the accelerated over relaxation (AOR) iteration method, a generalization of the AOR iteration method is presented to solve the absolute value equations (AVE), which is called the GAOR method. The convergence conditions of the GAOR method are obtained. Numerical experiments are presented in order to verify the feasibility of the GAOR method. [ABSTRACT FROM AUTHOR]

The energy of a graph G, denoted by E(G), is defined as the sum of absolute values of all eigenvalues of G. A graph G is called reciprocal if 1/≥ is an eigenvalue of G whenever λ is an eigenvalue of G. Further, if λ and 1 λ have the same multiplicities, for each eigenvalue λ, then it is called strong reciprocal. In (MATCH Commun. Math. Comput. Chem. 83 (2020) 631{633), it was conjectured that for every graph G with maximum degree Δ(G) and minimum degree ∞(G) whose adjacency matrix is non-singular, E(G) λ Δ(G) + ∞(G) and the equality holds if and only if G is a complete graph. Here, we prove the validity of this conjecture for some strong reciprocal graphs. Moreover, we show that if G is a strong reciprocal graph, then E(G) λ Δ(G) + ∞(G) - 1 2. Recently, it has been proved that if G is a reciprocal graph of order n and its spectral radius, ?, is at least 4λmin, where λmin is the smallest absolute value of eigenvalues of G, then E(G) λ n + 1 2. In this paper, we extend this result to almost all strong reciprocal graphs without the mentioned assumption. [ABSTRACT FROM AUTHOR]

In the paper [Optim. Methods Softw., 31 (2016), pp. 904{930] we derived first order (KKT) and second order (second order suffciency condition (SOSC)) optimality conditions for functions defined by evaluation programs involving smooth elementals and absolute values. In that analysis, a key assumption on the local piecewise linearization was the linear independence kink qualification (LIKQ), a generalization of the linear independence constraint qualification (LICQ) known from smooth nonlinear optimization. Firstly, we show here that under LIKQ and SOSC with strict complementarity, the natural algorithm of successive abs-linear minimization with a proximal term (SALMIN) achieves a linear rate of convergence. A version of SALMIN called LiPsMin has already been implemented and tested in [Math. Program., 158 (2016), pp. 383{415; Math. Program. (2018), https://doi.org/10.1007/s10107-018-1273-5]. Secondly, we observe that, even without any kink qualifications, local optimality of the nonlinear objective always requires local optimality of its piecewise linearization, and strict minimality of the latter is in fact equivalent to sharp minimality of the former. Moreover, we show that SALMIN will converge quadratically to such sharp minimizers, where the function exhibits linear growth. These results are independent of the particular function representation, and allow in particular duplications of switching variables and other intermediates. Furthermore, we derive for nonsharp minimizers necessary and suffcient optimality conditions without any kink qualification. Finally, we present numerical results to illustrate the obtained convergence results. [ABSTRACT FROM AUTHOR]

The SOR-like iteration method for solving the system of absolute value equations of finding a vector x such that A x - | x | - b = 0 with ν = ‖ A - 1 ‖ 2 < 1 is investigated. The convergence conditions of the SOR-like iteration method proposed by Ke and Ma (Appl. Math. Comput., 311:195–202, 2017) are revisited and a new proof is given, which exhibits some insights in determining the convergent region and the optimal iteration parameter. Along this line, the optimal parameter which minimizes ‖ T ν (ω) ‖ 2 with T ν (ω) = | 1 - ω | ω 2 ν | 1 - ω | | 1 - ω | + ω 2 ν and the approximate optimal parameter which minimizes an upper bound of ‖ T ν (ω) ‖ 2 are explored. The optimal and approximate optimal parameters are iteration-independent, and the bigger value of ν is, the smaller convergent region of the iteration parameter ω is. Numerical results are presented to demonstrate that the SOR-like iteration method with the optimal parameter is superior to that with the approximate optimal parameter proposed by Guo et al. (Appl. Math. Lett., 97:107–113, 2019). [ABSTRACT FROM AUTHOR]

In this paper, an analytical exact form of the ramp function is presented. This seminal function constitutes a fundamental concept of the digital signal processing theory and is also involved in many other areas of applied sciences and engineering. In particular, the ramp function is performed in a simple manner as the pointwise limit of a sequence of real and continuous functions with pointwise convergence. This limit is zero for strictly negative values of the real variable x, whereas it coincides with the independent variable x for strictly positive values of the variable x. Here, one may elucidate beforehand that the pointwise limit of a sequence of continuous functions can constitute a discontinuous function, on the condition that the convergence is not uniform. The novelty of this work, when compared to other research studies concerning analytical expressions of the ramp function, is that the proposed formula is not exhibited in terms of miscellaneous special functions, e.g., gamma function, biexponential function, or any other special functions, such as error function, hyperbolic function, orthogonal polynomials, etc. Hence, this formula may be much more practical, flexible, and useful in the computational procedures, which are inserted into digital signal processing techniques and other engineering practices.

An important scientific problem of the seventeenth and eighteenth centuries was to determine the figure of the earth. This problem attracted the attention of many notable people, one of whom was Roger Joseph Boscovich a Jesuit priest and natural scientist who formulated-and gave an algorithm for solving-linearly constrained optimization problems whose minimand is the sum of the absolute values of the errors, i.e., a special linear regression model. After first recounting some of the rich history of this development, the present expository note focuses on the method of Boscovich, exploring its interpretation as a variant of the simplex algorithm for linear programming applied to problems of that form. [ABSTRACT FROM AUTHOR]

The paper deals with hypergroupoids obtained from ternary relations.The correspondence between ternary relation and hypergroups, studied by the author, especially in the case when the relation ρ is symmetric and reflexive, is analyzed here in the most general context.A necessary and sufficient condition on a ternary relation ρ is obtained for the associated hypergroupoid to be a hypergroup or a join space. Extension of a hyperoperation associated with a ternary relation being employed to obtain a associated join space of the spherical geometry. [ABSTRACT FROM AUTHOR]

Finding the solution of the absolute value equation (AVE) A x − | x | = b has attracted much attention in recent years. In this paper, we propose a relaxed nonlinear PHSS-like iterative method, which is more efficient than the Picard-HSS iterative method for the AVE, and is a generalization of the nonlinear HSS-like iteration method for the AVE. By using the theory of nonsmooth analysis, we prove the convergence of the relaxed nonlinear PHSS-like iterative method for the AVE. Numerical experiments are given to demonstrate the feasibility, robustness and effectiveness of the relaxed nonlinear HSS-like method. [ABSTRACT FROM AUTHOR]

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We compute the leading asymptotics for the maximum of the (centered) logarithm of the absolute value of the characteristic polynomial, denoted Ψ N , of the Ginibre ensemble as the dimension of the random matrix N tends to ∞ . The method relies on the log-correlated structure of the field Ψ N and we obtain the lower-bound for the maximum by constructing a family of Gaussian multiplicative chaos measures associated with certain regularization of Ψ N at small mesoscopic scales. We also obtain the leading asymptotics for the dimensions of the sets of thick points and verify that they are consistent with the predictions coming from the Gaussian Free Field. A key technical input is the approach from Ameur et al. (Ann Probab 43(3):1157–1201, 2015) to derive the necessary asymptotics, as well as the results from Webb and Wong (Proc Lond Math Soc (3) 118(5):1017–1056, 2019). [ABSTRACT FROM AUTHOR]

Anderson localization is a universal phenomenon affecting non-interacting quantum particles in a disordered environment. In three spatial dimensions, theory predicts a quantum phase transition from localization to diffusion at a critical energy, the mobility edge, which depends on the disorder strength. Although it has been recognized already long ago as a prominent feature of disordered systems, a complete experimental characterization of the mobility edge is still missing. Here we report the measurement of the mobility edge for ultracold atoms in a disordered potential created by laser speckles. We are able to control both the disorder strength and the energy of the system, so as to probe the position of the localization threshold in the disorder-energy plane. Our results might allow a direct experiment-theory comparison, which is a prerequisite to study the even more challenging problem of disorder and interactions. [ABSTRACT FROM AUTHOR]

We describe a new two-step iterative method for solving the absolute value equations Ax−|x|=b, which is an NP-hard problem. This method is globally convergent under suitable assumptions. Numerical examples are given to demonstrate the effectiveness of the method. [ABSTRACT FROM AUTHOR]

Works by Celik and Abur suggest a weighted least absolute value state estimation with transformations (WLAV-T) for attaining insensitiveness of state estimation (SE) to bad measurements by mitigating the effect of leverage points. To further improve its applicability, this letter proposes a systematic approach to compute the optimal rotation angles and scaling factors of the WLAV-T, deriving a robust WLAV estimation approach with optimal transformations (WLAV-OT). The proposed approach has been preliminarily tested with promising results. [ABSTRACT FROM PUBLISHER]