A Mackey Imprimitivity Theory for Algebraic Groups.
Menon’s identity is a classical identity involving gcd sums and the Euler totient function . A natural generalization of is the Klee’s function . We derive a Menon-type identity using Klee’s function and a generalization of the gcd function. This identity generalizes an identity given by Y. Li and D. Kim (2017).
We define semantically a partial multiplication on the lattice of all e–varieties of regular semigroups. In the case that the first factor is an e–variety of orthodox semigroups we describe our multiplication syntactically in terms of biinvariant congruences.
A multiplication of e-varieties of regular -solid semigroups by inverse semigroup varieties is described both semantically and syntactically. The associativity of the multiplication is also proved.
It is studied how taking the inverse image by a sliding block code affects the syntactic semigroup of a sofic subshift. The main tool are ζ-semigroups, considered as recognition structures for sofic subshifts. A new algebraic invariant is obtained for weak equivalence of sofic subshifts, by determining which classes of sofic subshifts naturally defined by pseudovarieties of finite semigroups are closed under weak equivalence. Among such classes are the classes of almost finite type subshifts...
Let be a finite group and a prime number. We prove that if is a finite group of order such that has an irreducible character of degree and we know that has no irreducible character such that , then is isomorphic to . As a consequence of our result we prove that is uniquely determined by the structure of its complex group algebra.
Let be a finite group and the set of numbers of elements with the same order in . In this paper, we prove that a finite group is isomorphic to , where is one of the Mathieu groups, if and only if the following hold: (1) , (2) .