Results 1 - 10 of 4968
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[en] We show that recent criticism of a formula for diaganol operator equivalents (OE's) is unfounded. We generalise this formula to derive off-diagonal OE's, sup(j)Tsup(m)sub(l), as a finite polynomial in Jsub(z), and claim that this is a definitive formula for the sup(j)Tsup(m)sub(l). (orig.)
[en] A conference in operator theory and its applications commemorating the 100th anniversary of the birth of the distinguished German mathematician Otto Toeplitz, organized by the University of Tel Aviv together with German Mathematical Society, took place in Tel Aviv, Israel, from May 11th to 15th, 1981. I give here a broad very subjective overview of the proceedings of the conference for the benefit of readers of TTSP; for those interested in further details, a forthcoming volume in the Birkhaeuser series Operator Theory: Advances and Applications will consist of expanded written versions of most of the talks given at the conference
[en] Various forms of the q-boson are explained and their hidden symmetry revealed by transformations using the exponential phase operator. Both the one-component and the multicomponent q-bosons are discussed. As a byproduct, we obtain a new boson algebra having a shifted vacuum structure and define a global operator U(1) gauge transformation. (author)
[en] The Moyal bracket is an exemplification of Weyl's correspondence to formulate quantum mechancis in terms of Wigner function. Here we present a formalism of Weyl-ordered operator Moyal bracket by virtue of the method of integral within a Weyl ordered product of operators and the Weyl ordering operator formula.
[en] Accurate estimates are derived for the best approximation to the operator of the second mixed derivative on some classes of functions of two variables. These classes are defined by partial derivatives of the second and third orders
[en] The existence and structure of finite groups with four independent generators have been considered in this note when two of the generators are of order 2 and one is of odd prime order p. The defining relations of these groups are expressed by means of some simple parameters which are related by congruence and divisibility relations. (author)
[en] The paper is devoted to 2-local derivations on matrix algebras over unital semi-prime Banach algebras. For a unital semi-prime Banach algebra A with the inner derivation property we prove that any 2-local derivation on the algebra M_2_"n (A), n ≥ 2, is a derivation. We apply this result to AW*-algebras and show that any 2-local derivation on an arbitrary AW*-algebra is a derivation. (paper)
[en] In this paper we study the equiconvergence of expansions in trigonometric Fourier series and in eigenfunctions and associated functions of an integral operator whose kernel has discontinuities of the first kind on broken lines formed from the sides and diagonals of the squares obtained by dividing the unit square into n2 equal squares.