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Noether's Theorem and Symmetry
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Year: 2020 Publisher: [Place of publication not identified] : MDPI - Multidisciplinary Digital Publishing Institute,

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Abstract

In Noether's original presentation of her celebrated theorem of 1918, allowances were made for the dependence of the coefficient functions of the differential operator which generated the infinitesimal transformation of the Action Integral upon the derivatives of the dependent variable(s), the so-called generalized, or dynamical, symmetries. A similar allowance is to be found in the variables of the boundary function, often termed a gauge function by those who have not read the original paper. This generality was lost after texts such as those of Courant and Hilbert or Lovelock and Rund confined attention to only point transformations. In recent decades, this diminution of the power of Noether's Theorem has been partly countered, in particular, in the review of Sarlet and Cantrijn. In this Special Issue, we emphasize the generality of Noether's Theorem in its original form and explore the applicability of even more general coefficient functions by allowing for nonlocal terms. We also look at the application of these more general symmetries to problems in which parameters or parametric functions have a more general dependence upon the independent variables.

Keywords

Symmetry.


Book
Discrete Mathematics and Symmetry
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Year: 2020 Publisher: Basel : MDPI - Multidisciplinary Digital Publishing Institute,

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Some of the most beautiful studies in Mathematics are related to Symmetry and Geometry. For this reason, we select here some contributions about such aspects and Discrete Geometry. As we know, Symmetry in a system means invariance of its elements under conditions of transformations. When we consider network structures, symmetry means invariance of adjacency of nodes under the permutations of node set. The graph isomorphism is an equivalence relation on the set of graphs. Therefore, it partitions the class of all graphs into equivalence classes. The underlying idea of isomorphism is that some objects have the same structure if we omit the individual character of their components. A set of graphs isomorphic to each other is denominated as an isomorphism class of graphs. The automorphism of a graph will be an isomorphism from G onto itself. The family of all automorphisms of a graph G is a permutation group.


Book
Calculus of Variations, Optimal Control, and Mathematical Biology A Themed Issue Dedicated to Professor Delfim F. M. Torres on the Occasion of His 50th Birthday
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Year: 2023 Publisher: Hershey, PA : IGI Global,

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This reprint is dedicated to Professor Delfim F. M. Torres for his 50th birthday. Professor Delfim F. M. Torres is a recognized researcher, particularly in the calculus of variations, optimal control, and mathematical biology. In this reprint, several studies in his research fields are presented.


Book
Axisymmetry in Mechanical Engineering
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ISBN: 303656490X 3036564896 Year: 2023 Publisher: [Place of publication not identified] : MDPI - Multidisciplinary Digital Publishing Institute,

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The reprint is devoted to the phenomena associated with exact or approximate axial symmetry in different areas of technical physics and mechanical engineering science. How can the symmetry of the problem be used most efficiently for its analysis? Why is the symmetry broken or why is it still approximately retained? These and other questions are discussed based on systems from different fields of engineering.

Keywords

Symmetry --- History. --- Aesthetics --- Proportion


Book
Polyhedral Structures, Symmetry, and Applications
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Year: 2018 Publisher: Basel : MDPI - Multidisciplinary Digital Publishing Institute,

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Symmetry is an intriguing phenomenon manifesting itself in art, nature, and the mind. This Special Issue book features 19 articles about discrete geometric and combinatorial polyhedral structures, with symmetry as the unifying theme. These articles present an attractive mix of topics and have appeared in two related Special Issues of Symmetry, on "Polyhedra" in 2012/2013 and on "Polyhedral Structures" in 2016/2017. Specific topic areas covered include polyhedra, tilings, and crystallography; abstract polyhedra, maps on surfaces, and graphs; and polyhedral structures, arts, and architectural design.


Book
Symmetry in Mathematical Analysis and Functional Analysis
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ISBN: 3036565906 3036565914 Year: 2023 Publisher: Basel, Switzerland : MDPI - Multidisciplinary Digital Publishing Institute,

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The present reprint provides some theoretical results (and their applications) in the fields of mathematical analysis and functional analysis, in which the concept of symmetry plays an essential role. More specifically, various problems are investigated in areas, such as: optimization problems, polynomial approximation on unbounded subsets, moment problems, variational inequalities, evolutionary problems, dynamical systems, generalized convexity, partial differential equations, and special spaces of self-adjoint operators. With various examples and applications to complement and substantiate the mathematical developments, the present reprint is a valuable guide for researchers, engineers, and students in the field of mathematics, operations research, optimal control science, artificial intelligence, management science, and economics.


Book
Symmetric distributions, moments and applications
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ISBN: 3036558489 3036558470 Year: 2023 Publisher: Basel : MDPI,

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This reprint is focuses on distributions and moments and publish papers on the theory and applications of probability and statistics. Papers include original results of symmetric random walks and their characterization, stochastic processes, stochastic integrals, martingales, probability inequalities, statistics parameter estimation, stochastic differential equations, fractional Brownian motions, continuous time random walk models, anomalous diffusion models, Black-Scholes models, Monte Carlo methods, etc. This Special Issue is focused on concepts and techniques and is oriented toward a broad spectrum of applied mathematics and sciences. Focused review articles reviewed the state of the art and identify upcoming challenges and promising solutions for the scientific community.


Book
Symmetry Measures on Complex Networks
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ISBN: 3038424994 3038424986 Year: 2017 Publisher: MDPI - Multidisciplinary Digital Publishing Institute

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Symmetry is found everywhere, to a greater or lesser degree. It is essential in all sciences and also as the basic substrate in all arts. The same happens with Complex Networks, which are the majority of all those that interest for advanced knowledge, that is, for research. That is why these two themes have been unified here, whose intersection we are dealing with: in its first part, of fundamentals, and in its second part of applications, which are multiple in the world today.


Book
Lie and non-Lie Symmetries: Theory and Applications for Solving Nonlinear Models
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ISBN: 3038425273 3038425265 Year: 2017 Publisher: MDPI - Multidisciplinary Digital Publishing Institute

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Since the end of the 19th century when the prominent Norwegian mathematician Sophus Lie created the theory of Lie algebras and Lie groups and developed the method of their applications for solving differential equations, his theory and method have continuously been the research focus of many well-known mathematicians and physicists. This book is devoted to recent development in Lie theory and its applications for solving physically and biologically motivated equations and models. The book contains the articles published in two Special Issue of the journal Symmetry, which are devoted to analysis and classification of Lie algebras, which are invariance algebras of real-word models; Lie and conditional symmetry classification problems of nonlinear PDEs; the application of symmetry-based methods for finding new exact solutions of nonlinear PDEs (especially reaction-diffusion equations) arising in applications; the application of the Lie method for solving nonlinear initial and boundary-value problems (especially those for modelling processes with diffusion, heat transfer, and chemotaxis).


Book
Symmetry in Vision
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ISBN: 3038424978 303842496X Year: 2017 Publisher: MDPI - Multidisciplinary Digital Publishing Institute

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Symmetry has a central role in the study of vision. The concept of symmetry has an ancient origin in considerations of visual appearance; in modern times, abstracted and formalized into Group Theory, it has found spectacular applications, far beyond the visible; but its importance for vision persists in many ways including: • As a non-accidental feature of an image that cues affordances, 3D structure or the semantic categories of object present. • As a redundant aspect of an image which many be exploited for simplicity and compactness of encoding. • As a salient feature that draws attention, and evokes distinctive brain responses. • As a constraint on priors on the distribution of structures to be found in the natural world. • As an aesthetic principle. • As a design principle for vision systems. • The original idea for a Special Issue came from a symposium at the European Conference in Visual Perception, in 2015, on the topic of brain responses to visual symmetry, but we have now extended the scope. This Special Issue is devoted to provide a shared place for cutting edge studies on how and why symmetry is processed and exploited by biological and artificial visual systems.

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