Generalizations of some conjectures of Sun on the relations between N(a, b, c, d; n) and T(a, b, c, d; n)

The Ramanujan Journal - We derive some new finite sums involving the sequence $$s_{2}\left( n\right) ,$$ the sum-of-digits of the expansion of n in base 2. These functions allow us to generalize...     

Fluid thermodynamics,energy redistribution law,two-dimensional condensate,and <Emphasis Type="Italic">T</Emphasis> map

In detail, we consider the concurrence of experimental data with the results of calculations in accordance with formulas we previously derived for a real gas. We formulate the energy redistribution law following from the occurrence of dimers. We state a theorem on the two-dimensional condensate for any gas and describe the process of transition to equilibrium thermodynamics as the pressure under the piston increases.     

χ‐bounds,operations, and chords

A long unichord in a graph is an edge that is the unique chord of some cycle of length at least 5. A graph is long unichord free if it does not contain any long unichord. We prove a structure theorem for long unichord free graph. We give an time algorithm to recognize them. We show that any long unichord free graph G can be colored with at most colors, where ω is the maximum number of pairwise adjacent vertices in G.     

Invariants of knots,surfaces in R<Superscript>3</Superscript>, and foliations

We give a survey of some known results related to combinatorial and geometric properties of finite-order invariants of knots in a three-dimensional space. We study the relationship between Vassiliev invariants and some classical numerical invariants of knots and point out the role of surfaces in the investigation of these invariants. We also consider combinatorial and geometric properties of essential tori in standard position in closed braid complements by using the braid foliation technique developed by Birman, Menasco, and other authors. We study the reductions of link diagrams in the context of finding the braid index of links. __________ Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 59, No. 9, pp. 1239–1252, September, 2007.     

Area,coarea, and approximation in <Emphasis Type="Italic">W</Emphasis><Superscript>1,1</Superscript>

Let Ω⊂ℝ ⁿ be an arbitrary open set. We characterize the space W ^1,1 _loc(Ω) using variants of the classical area and coarea formulas. We use these characterizations to obtain a norm approximation and trace theorems for functions in the space W ^1,1(ℝ ⁿ ).     

Fredholm determinants,Jimbo‐Miwa‐Ueno τ‐functions,and representation theory

The authors show that a wide class of Fredholm determinants arising in the representation theory of “big” groups, such as the infinite‐dimensional unitary group, solve Painlevé equations. Their methods are based on the theory of integrable operators and the theory of Riemann‐Hilbert problems. © 2002 Wiley Periodicals, Inc.     

Spencer <Emphasis Type="Italic">δ</Emphasis>-cohomology,Restrictions, Characteristics and Involutive Symbolic PDEs

We generalize the notion of involutivity to systems of differential equations of different orders and show that the classical results relating involutivity, restrictions, characteristics and characteristicity, known for first order systems, extend to the general context. This involves, in particular, a new definition of strong characteristicity. The proof exploits a spectral sequence relating Spencer δ-cohomology of a symbolic system and its restriction to a non-characteristic subspace.      

Two‐Timing Hypothesis,Distinguished Limits,Drifts, and Pseudo‐Diffusion for Oscillating Flows

The aim of this paper is: using the two‐timing method to study and classify the multiplicity of distinguished limits and asymptotic solutions for the advection equation with a general oscillating velocity field. Our results are:

• (i) the dimensionless advection equation that contains two independent small parameters, which represent the ratio of two characteristic time‐scales and the spatial amplitude of oscillations; the related scaling of the variables and parameters uses the Strouhal number;
• (ii) an infinite sequence of distinguished limits has been identified; this sequence corresponds to the successive degenerations of a drift velocity;
• (iii) we have derived the averaged equations and the oscillatory equations for the first four distinguished limits; derivations are performed up to the fourth orders in small parameters;
• (v) we have shown, that each distinguished limit generates an infinite number of parametric solutions; these solutions differ from each other by the slow time‐scale and the amplitude of the prescribed velocity;
• (vi) we have discovered the inevitable presence of pseudo‐diffusion terms in the averaged equations, pseudo‐diffusion appears as a Lie derivative of the averaged tensor of quadratic displacements; we have analyzed the matrix of pseudo‐diffusion coefficients and have established its degenerated form and hyperbolic character; however, for one‐dimensional cases, the pseudo‐diffusion can appear as ordinary diffusion;
• (vii) the averaged equations for four different types of oscillating velocity fields have been considered as the examples of different drifts and pseudo‐diffusion;
• (viii) our main methodological result is the introduction of a logical order into the area and classification of an infinite number of asymptotic solutions; we hope that it can help in the study of the similar problems for more complex systems;
• (ix) our study can be used as a test for the validity of the two‐timing hypothesis, because in our calculations we do not employ any additional assumptions.

     

On an anti‐Ramsey problem of Burr,Erdős,Graham, and T. Sós

Given a graph L, in this article we investigate the anti‐Ramsey number χ_S(n,e,L), defined to be the minimum number of colors needed to edge‐color some graph G(n,e) with n vertices and e edges so that in every copy of L in G all edges have different colors. We call such a copy of L totally multicolored (TMC). In 7 among many other interesting results and problems, Burr, Erd?s, Graham, and T. Sós asked the following question: Let L be a connected bipartite graph which is not a star. Is it true then that In this article, we prove a slightly weaker statement, namely we show that the statement is true if L is a connected bipartite graph, which is not a complete bipartite graph. © 2006 Wiley Periodicals, Inc. J Graph Theory 52: 147–156, 2006     

R‐weak commutativity,examples, and applications

The aim of this article is to define a new contraction and its variants in non‐Archimedean Menger probabilistic metric‐spaces, and utilize them to establish the existence of a combined common fixed point illustrating with examples. We also apply our result to integral type equations, Volterra type integral equations, damped harmonic oscillators, and nonlinear matrix equations.     

An information‐theoretic primer on complexity,self‐organization,and emergence

Complex Systems Science aims to understand concepts like complexity, self‐organization, emergence and adaptation, among others. The inherent fuzziness in complex systems definitions is complicated by the unclear relation among these central processes: does self‐organisation emerge or does it set the preconditions for emergence? Does complexity arise by adaptation or is complexity necessary for adaptation to arise? The inevitable consequence of the current impasse is miscommunication among scientists within and across disciplines. We propose a set of concepts, together with their possible information‐theoretic interpretations, which can be used to facilitate the Complex Systems Science discourse. Our hope is that the suggested information‐theoretic baseline may promote consistent communications among practitioners, and provide new insights into the field. Published 2008 Wiley Periodicals, Inc. Complexity, 2009     

Generalized convex spaces, <Emphasis Type="Italic">L</Emphasis>-spaces,and <Emphasis Type="Italic">FC</Emphasis>-spaces

We show that FC-spaces due to Ding are particular types of L-spaces due to Ben-El-Mechaiekh et al., and hence particular types of G-convex spaces. Some counter-examples are given and related matters are also discussed.     

Motion, speed, and other ideas that “should be put in books”

This paper focuses on a portion of a research project involving a group of inner-city middle school students who used SimCalc simulation software over the course of an entire school year to investigate ideas relating to graphical representations of motion and speed. The classroom environment was one in which students openly defended and justified their thinking as they actively explored and solved rich mathematical problems. The activities, generally speaking, involved functions that were intended to tap students’ real world intuitions as well as prior mathematical skills and understandings about speed, motion, and other graphical representations that underlie the mathematics of motion. Results indicate that these students did build ideas related to those concepts. This paper will provide documentation of the ways in which these students interpreted graphical representations involving linear and quadratic functions that are associated with constant and linearly changing velocities, respectively.