W ∗ k = {x ǫX|xǫ Domain (A(a1) . . .A (ak)) for all a1, . . . , akǫA} is dense inX in theweak* topology. Let {e1, . . . , en} be a basis forA and setAi = A(ei), A ∗ i = A(ei). If α = (α1, . . . , αk), 1 ≤ αi ≤ n, is a sequence of integers we denote a product such as Aα1 . . .Aαk byAα; |α| = k is the length ofα. The operatorB ◦ = Σ|α|≤maαAα (the coefficients are complex numbers) is defined on Wm...

In this paper, we prove the existence of a particular diagonalization for normal bounded operators defined on subspaces $$L^2({\mathfrak {S}})$$ where $${\mathfrak {S}}$$ is second countable LCA group. The act are invariant under action group $$\Gamma $$ which semi-direct product uniform lattice with discrete automorphisms. This class includes crystal groups important in applications as mode...

With every Lie semi-group, Π, possessing certain regularity properties, there is associated a Lie algebra, A; and with every strongly continuous representation of Π in a Banach space there is associated a representation A(a) of A. Certain theorems regarding this representation are established. The above theorems are valid for a representation of a Lie group also. In this case, it is shown that ...

a subset of real Euclidean n-space, En, by (p, q) → F (p − q) = p ◦ q. In this note we shall be concerned with a representation T (.) of π as a semi-group of bounded linear operators on a Banach space X. More particularly, we suppose that postulates P1, P2, P3, P5, and P6 of chapter 25 of (2) are satisfied so that, by Theorem 25.3.1 of that book, there is a continuous function, f(.), defined on...

for two normal edge-transitive cayley graphs on groups h and k which have no common direct factor and gcd(jh=h ′j; jz(k)j) = 1 = gcd(jk=k ′j; jz(h)j), we consider four standard products of them and it is proved that only tensor product of factors can be normal edge-transitive.

Recent work of Gromov, Epstein, Cannon, Thurston and many others has generated strong interest in the geometric and algorithmic structure of finitely generated infinite groups. (See [16],[17] and [14].) Many of these structures are preserved by taking graph products. The graph product of groups (not to be confused with the fundamental group of a graph of groups) is a product mixing direct and f...

Let A be the collection of groups which can be assembled from infinite cyclic groups using the binary operations free and direct product. These groups can be described in several ways by graphs. The group (Z ∗Z)×(Z ∗Z) has been shown by [1] to have a rich subgroup structure. In this article we examine subgroups of A–groups. DefineA to be the smallest class of groups which contains the infinite ...

The above theorems are valid for a representation of a Lie group also. In this case, it is shown that it is possible to extend the representation to elliptic elements of the universal enveloping algebra. It is also shown that the representatives of the strongly elliptic elements of the universal enveloping algebra are the infinitesimal generators of holomorphic semi-groups. Integral representat...