A generating function for fatgraphs
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.
Suppose is a prime number and is a commutative ring with unity of characteristic 0 in which is not a unit. Assume that and are -primary abelian groups such that the respective group algebras and are -isomorphic. Under certain restrictions on the ideal structure of , it is shown that and are isomorphic.
Let be an associative ring with identity and let denote the Jacobson radical of . is said to be semilocal if is Artinian. In this paper we give necessary and sufficient conditions for the group ring , where is an abelian group, to be semilocal.
The notion of age of elements of complex linear groups was introduced by M. Reid and is of importance in algebraic geometry, in particular in the study of crepant resolutions and of quotients of Calabi–Yau varieties. In this paper, we solve a problem raised by J. Kollár and M. Larsen on the structure of finite irreducible linear groups generated by elements of age . More generally, we bound the dimension of finite irreducible linear groups generated by elements of bounded deviation. As a consequence...