Let DMAP be the class of locally compact groups that admit a (not necessarily continuous) embedding in a compact topological group, and let FIR be the class of locally compact groups all of whose continuous irreducible unitary representations are finite-dimensional. We prove that every almost connected DMAP group is an FIR group.

The main object of this paper is to present a family of q-series identities which involve some of the theta functions of Jacobi and Ramanujan. Each of these (presumably new) q-series identities reveals interesting relationships among three of the theta-type functions which stem from the celebrated Jacobi’s triple-product identity in a remarkably simple way. The q-results presented in this paper are

In the paper, we derive a formula expressing the reduced dynamics of the Wigner function using the dynamics of the Wigner function of a larger system. Here the latter system is assumed to be isolated and generating the dynamics of its subsystem.

The central factorial numbers of the second kind appear in the expansion of powers of x in terms of the central factorial sequence. In this paper, we introduce the central Bell numbers and polynomials associated with those central factorial numbers of the second kind and investigate some identities and properties of them.

A functional integral with respect to the Wiener measure that represents a solution of the Schrödinger equation with signed Hamiltonian is obtained. In turn, this integral is derived, using the analytic continuation with respect to the argument, from a similar integral for the corresponding heat equation.

One shows that the Feynman’s Path Integral designed for quantum mechanics has an analogous in classical mechanics, the so-called (min, +) Path Integral. This former is build on (min, +)-algebra and (min, +)-analysis which permit to handle in a linear way non-linear problems occurring in mathematical physics. The Hamilton-Jacobi equations and their solutions within this mathematical framework, are introduced

We study a nonlinear problem of gas filtration in a porous and weakly conducting medium that is used to model the overheating process in reactors. We obtain explicit estimates for the critical values of the similarity parameter of the problem which determine a condition for the existence of a steady-state cooling regime for a system open to atmosphere and a condition for global overheating. The bifurcation

Massless Dirac equation for spinor multiplets is minimally coupled with a unitary representation of an arbitrary compact semisimple gauge group. The spectrum of the quantized coupled Dirac Hamiltonian has a positive mass gap running along the classical energy scale.

This paper considers the plane-parallel motion of an elliptic foil in a fluid with a nonzero constant circulation under the action of external periodic forces and torque. The existence of the first integral is shown for the case in which there is no external torque and an external force acts along one of the principal axes of the foil. It is shown that, in the general case, in the absence of friction

Using a solution concept defined in the setting of a product of distributions, we consider the nonlinear equation f(t)ut + (u2)x = 0, where f is a continuous function. This equation can be regarded a generalization of Burgers inviscid equation and allows to study several kinds of interaction of δ-waves. If f(t) ≠ 0 for all t, collisions of δ-waves cannot exist. If f(t) = 0 for certain values of t,

We consider 3-dimensonal Schrödinger operators with complex potential. We obtain new trace formulas with new terms, associated with singular measure. In order to prove these results, we study analytic properties of a modified Fredholm determinant as a function from Hardy spaces in the upper half-plane. In fact, we reformulate spectral theory problems as problems of analytic functions from Hardy spaces

In the paper, the problem of propagation of waves generated by localized source on a two-dimensional lattice is studied. The discrete problem is reduced to a continuous Cauchy problem, and the answer for this problem is constructed using the modified Maslov’s canonical operator, including a neighborhood of the leading wave front. The strong and weak dispersion effects depending on the relationship

In the one-dimensional case, an asymptotic expansion with respect to the parameter for the Feynman integral in the Lee—Pomeransky representation, is obtained. The previously stated conjecture on how to obtain asymptotic series is proved, and the form of the terms of the series and the relationship of the series with Newton’s polyhedron of the polynomial participating in the integrand are determined

In this paper, we consider \({\mathcal A}\)-Fredholm and semi-\({\mathcal A}\)-Fredholm operators on Hilbert C*-modules over a W*-algebra \({\mathcal A}\) defined in [3] and [9]. Using the assumption that \({\mathcal A}\) is a W*-algebra (rather than an arbitrary C*-algebra), we obtain a generalization of Schechter—Lebow characterization of semi-Fredholm operators and a generalization of the “punctured

The main result is that a Lie group admitting a (not necessarily continuous) embedding in an amenable Lie group is amenable.

The notions of “hole” and “vacuum” in various branches of science are considered. A philosophical generalization of these notions on the basis of examples from physics, history, and linguistics is presented. Some aspects of the further development of these notions in mathematical logic, thermodynamics of nuclear matter, and other branches of science are sketched.

In the present note, we show that, for some special classes of external flows, the short-wave asymptotic behavior of the solution of linearized equations of relativistic gas dynamics can be described rather explicitly.

We consider Sobolev problems (problems for an elliptic operator on a closed manifold with conditions on a closed submanifold) for the case in which these conditions are of nonlocal nature and include weighted spherical means of the unknown function over spheres of a given radius. For such problems, we establish a criterion for the Fredholm property and, in some special cases, obtain index formulas

We consider a d-dimensional harmonic crystal, d ⩾ 1, and study the Cauchy problem with random initial data. The distribution μt of the solution at time t ∈ ℝ is studied. We prove the convergence of correlation functions of the measures μt to a limit for large times. The explicit formulas for the limiting correlation functions and for the energy current density (in the mean) are obtained in terms of

New order estimates for the Kolmogorov, linear, and Gel’fand diameters of the Sobolev weight classes on a domain satisfying John’s condition in the Lebesgue weighted space are obtained.