A Differential Calculus on the (h,j)-Deformed Z3-Graded Superplane

In this work, Z₃-graded quantum (h, j)-superplane is introduced with a help of proper singular g matrix and a Z₃-graded calculus is constructed over this new h-superplane. A new Z₃-graded (h, j)-deformed quantum (super)group is constructed via the obtained calculus.     

Stability relative to a set and to the whole space revisited

In [1] P. Seibert suggested without proof some theorems on stability. These theorems involved two new concepts: The first is a local stability of a subset Y of a metric space X on a subset Z of Y. The second is a notion of conditionally attracting set Y ⊆ X on Z ⊆ Y. Using the first of Seibert's concepts, we suggest new theorems and provide the corresponding proofs. However, our theorems are logically independent of those of Seibert. In addition, a proof of a criterion on local stability suggested by Seibert is given.     

Relative difference sets fixed by inversion (ii)—character theoretical approach

In this paper, we continue our investigation of relative difference sets fixed by inversion. We exclusively focus our attention on abelian groups. New necessary conditions are obtained and a new family of such relative difference sets with forbidden subgroup Z/4Z is constructed. The methods we use are character theory of abelian groups and Galois rings over Z/4Z.     

New solutions to the Hurwitz problem on square identities

The Hurwitz problem of composition of quadratic forms, or of “sum of squares identity” is tackled with the help of a particular class of (Z/2Z)ⁿ-graded non-associative algebras generalizing the octonions. This method provides explicit formulas for the classical Hurwitz-Radon identities and leads to new solutions in a neighborhood of the Hurwitz-Radon identities.     

Integrals involving products of Airy functions, their derivatives and Bessel functions

A new integral representation of the Hankel transform type is deduced for the function Fn(x,Z)=Zn−1Ai(x−Z)Ai(x+Z) with x∈R, Z>0 and n∈N. This formula involves the product of Airy functions, their derivatives and Bessel functions. The presence of the latter allows one to perform various transformations with respect to Z and obtain new integral formulae of the type of the Mellin transform, K-transform, Laplace and Fourier transform. Some integrals containing Airy functions, their derivatives and Chebyshev polynomials of the first and second kind are computed explicitly. A new representation is given for the function ²|Ai(z)| with z∈C.     

Applications of a theorem by Ky Fan in the theory of graph energy

The energy of a graph G is equal to the sum of the absolute values of the eigenvalues of G, which in turn is equal to the sum of the singular values of the adjacency matrix of G. Let X, Y, and Z be matrices, such that X+Y=Z. The Ky Fan theorem establishes an inequality between the sum of the singular values of Z and the sum of the sum of the singular values of X and Y. This theorem is applied in the theory of graph energy, resulting in several new inequalities, as well as new proofs of some earlier known inequalities.     

The Möbius function and the residue theorem

A classical conjecture of Bouniakowsky says that a non-constant irreducible polynomial in Z[T] has infinitely many prime values unless there is a local obstruction. Replacing Z[T] with κ[u][T], where κ is a finite field, the obvious analogue of Bouniakowsky's conjecture is false. All known counterexamples can be explained by a new obstruction, and this obstruction can be used to fix the conjecture. The situation is more subtle in characteristic 2 than in odd characteristic. Here, we illustrate the general theory for characteristic 2 in some examples.     

General frame constructions for Z-cyclic triplewhist tournaments

Frames are useful in dealing with resolvable designs such as resolvable balanced incomplete block designs and triplewhist tournaments. Z-cyclic triplewhist tournament frames are also useful in the constructions of Z-cyclic triplewhist tournaments. In this paper, the concept of an (h₁,h₂,…,hn;u)-regular Z-cyclic triplewhist tournament frame is defined, and used to establish several quite general recursive constructions for Z-cyclic triplewhist tournaments. As corollaries, we are able to unify many known constructions for Z-cyclic triplewhist tournaments. As an application, some new Z-cyclic triplewhist tournament frames and Z-cyclic triplewhist tournaments are obtained. The known existence results of such designs are then extended.     

Singular integrals associated to the Laplacian on the affine groupax+b

We consider singular integral operators of the form (a)Z ₁L^?1Z₂, (b)Z ₁Z₂L^?1, and (c)L ^?1Z₁Z₂, whereZ ₁ andZ ₂ are nonzero right-invariant vector fields, andL is theL ²-closure of a canonical Laplacian. The operators (a) are shown to be bounded onL ^p for allp∈(1, ∞) and of weak type (1, 1), whereas all of the operators in (b) and (c) are not of weak type (p, p) for anyp∈[1, ∞).     

Extension of continuous functions in digital spaces with the Khalimsky topology

The digital space Zn equipped with Efim Khalimsky's topology is a connected space. We study continuous functions Zn⊃A→Z, from a subset of Khalimsky n-space to the Khalimsky line. We give necessary and sufficient condition for such a function to be extendable to a continuous function Zn→Z. We classify the subsets A of the digital plane such that every continuous function A→Z can be extended to a continuous function on the whole plane.     

Plane partitions IV: A conjecture of Mills—Robbins—Rumsey

In this paper we consider a problem posed by W Mills D Robbins and H Rumsey for a certain plane partition generating functionZ _n (x, m) The special caseZ _n (1,m) is the generating function that arose in the weak Macdonald conjecture Mills—Robbins—Rumsey conjectured thatZ _n (2,m) also possesses a nice finite product representation Their conjecture is proved as Theorem 1 The method of proof resembles that of the evaluation ofZ _n (1,m) given previously Many results for the₃ F ₂ hypergeometric function are required including Whipple's theorem, the Pfaff-Saalschutz summation and contiguous relations In passing we note that our Lemma 2 provides a new and simpler representation ofZ _n (2,m) as a determinant $$Z_n (2,m) = \det \left( {\delta _{ij} + \sum\limits_{t = 0}^1 {\left( {\mathop {m + j + t}\limits_t } \right)} \left( {\mathop {m + t}\limits_{m + t} } \right)} \right)_{0 \leqq ij \leqq n - 1} $$ Conceivably this new representation may provide new interpretations of the combinatorial significance ofZ _n (2,m) In the final analysis, one would like a combinatorial explanation ofZ _n (2,m) that would provide an algorithmic proof of the Mills Robbins—Rumsey conjecture     

Differential characters in K-theory

We define the new notion of R/Z-differential K-characters and study some properties. In particular, we show that the spectral eta invariant is an R/Z-secondary invariant in this theory.     

A concavity inequality for symmetric norms

We review some recent convexity results for Hermitian matrices and we add a new one to the list: Let A be semidefinite positive, let Z be expansive, Z^∗Z?I, and let f:[0,∞)→[0,∞) be a concave function. Then, for all symmetric norms

‖f(Z^∗AZ)‖?‖Z^∗f(A)Z‖.     

Plane partitions IV: A conjecture of Mills—Robbins—Rumsey

In this paper we consider a problem posed by W Mills D Robbins and H Rumsey for a certain plane partition generating functionZ _n (x, m) The special caseZ _n (1,m) is the generating function that arose in the weak Macdonald conjecture Mills—Robbins—Rumsey conjectured thatZ _n (2,m) also possesses a nice finite product representation Their conjecture is proved as Theorem 1 The method of proof resembles that of the evaluation ofZ _n (1,m) given previously Many results for the₃ F ₂ hypergeometric function are required including Whipple's theorem, the Pfaff-Saalschutz summation and contiguous relations In passing we note that our Lemma 2 provides a new and simpler representation ofZ _n (2,m) as a determinant $$Z_n (2,m) = \det \left( {\delta _{ij} + \sum\limits_{i = 0}^l {\left( {\begin{array}{*{20}c} {m + j + t} \\ t \\ \end{array} } \right)\left( {\begin{array}{*{20}c} {m + i} \\ {m + t} \\ \end{array} } \right)} } \right)_{0 \leqq ij \leqq n - 1} $$ Conceivably this new representation may provide new interpretations of the combinatorial significance ofZ _n (2,m) In the final analysis, one would like a combinatorial explanation ofZ _n (2,m) that would provide an algorithmic proof of the Mills Robbins—Rumsey conjecture     

On multifractality and time subordination for continuous functions

Let Z:[0,1]→R be a continuous function. This paper relates to the existence of a decomposition of Z as Z=g○f, where g:[0,1]→R is a monofractal function with exponent 0<H<1 and f:[0,1]→[0,1] is a time subordinator, i.e. the integral of a positive Borel measure supported by [0,1]. An equivalent question consists of searching for a (multifractal) parametrization of Z which transforms Z into a monofractal function. We establish that such a decomposition can be found for a large class of functions which includes the usual examples of multifractal functions.We find an interesting relationship between self-similar functions and self-similar measures as an application of our results.Our theorems yield new insights in the understanding of the multifractal behaviour of functions, giving a significant role to the regularity analysis of Borel measures.     

Factoring weakly compact operators

The main result is that every weakly compact operator between Banach spaces factors through a reflexive Banach space. Applications of the result and technique of proof include new results (e.g., separable conjugate spaces embed isomorphically in spaces with boundedly complete bases; convex weakly compact sets are affinely homeomorphic to sets in a reflexive space) and simple proofs of known results (e.g., there is a reflexive space failing the Banach-Saks property; if X is separable, then $\text{X =}\text{Z}{}^7\text{Z}$ for some Z; there is a separable space which does not contain l₁ whose dual is nonseparable).     

Borsuk presentations and the fixed-point index

We develop a theory of fixed-point index for maps f: X → X such that the fixed-point set of f is contained in a compact invariant set A, and A has a Borsuk presentation as an intersection of a decreasing sequence of ANR Z_n ? X and Z_{n + 1} is a retract of Z_n.     

Well-posedness of a class of perturbed optimization problems in Banach spaces

Let X be a Banach space and Z a nonempty subset of X. Let J:Z→R be a lower semicontinuous function bounded from below and p?1. This paper is concerned with the perturbed optimization problem of finding z₀∈Z such that ‖x−z₀p^‖+J(z₀)=infz∈Z{‖x−zp^‖+J(z)}, which is denoted by minJ(x,Z). The notions of the J-strictly convex with respect to Z and of the Kadec with respect to Z are introduced and used in the present paper. It is proved that if X is a Kadec Banach space with respect to Z and Z is a closed relatively boundedly weakly compact subset, then the set of all x∈X for which every minimizing sequence of the problem minJ(x,Z) has a converging subsequence is a dense Gδ-subset of X?Z₀, where Z₀ is the set of all points z∈Z such that z is a solution of the problem minJ(z,Z). If additionally p>1 and X is J-strictly convex with respect to Z, then the set of all x∈X for which the problem minJ(x,Z) is well-posed is a dense Gδ-subset of X?Z₀.     

Poisson statistics via the Chinese Remainder Theorem

We consider the distribution of spacings between consecutive elements in subsets of Z/qZ, where q is highly composite and the subsets are defined via the Chinese Remainder Theorem. We give a sufficient criterion for the spacing distribution to be Poissonian as the number of prime factors of q tends to infinity, and as an application we show that the value set of a generic polynomial modulo q has Poisson spacings. We also study the spacings of subsets of Z/q₁q₂Z that are created via the Chinese Remainder Theorem from subsets of Z/q₁Z and Z/q₂Z (for q₁,q₂ coprime), and give criteria for when the spacings modulo q₁q₂ are Poisson. Moreover, we also give some examples when the spacings modulo q₁q₂ are not Poisson, even though the spacings modulo q₁ and modulo q₂ are both Poisson.