Non-normal abelian subalgebras

On non-normal non-abelian subgroups of finite groups

‎In this paper we prove that a finite group $G$ having at most three‎ ‎conjugacy classes of non-normal non-abelian proper subgroups is‎ ‎always solvable except for $Gcong{rm{A_5}}$‎, ‎which extends Theorem 3.3‎ ‎in [Some sufficient conditions on the number of‎ ‎non-abelian subgroups of a finite group to be solvable‎, ‎Acta Math‎. ‎Sinica (English Series) 27 (2011) 891--896.]‎. ‎Moreover‎, ‎we s...

Maximal Abelian Subalgebras of O N

We consider maximal abelian subalgebras of O n which are invariant to the standard circle action. It turns out that these are all contained in the zero grade of O n. Then we consider shift invariant maximal abelian subalgebras of the zero grade, which are also invariant to a " second shift " map, and show that these are just infinite tensor products of diagonal matrices in the standard UHF pict...

Conditional Expectations onto Maximal Abelian *-subalgebras

We determine when there is a unique conditional expectation from a semifinite von Neumann algebra onto a singly-generated maximal abelian *-subalgebra. Our work extends the results of Kadison and Singer via new methods, notably the observation that a unique conditional expectation onto a singly-generated maximal abelian *-subalgebra must be normal.

The non-abelian tensor product of normal crossed submodules of groups

In this article, the notions of non-abelian tensor and exterior products of two normal crossed submodules of a given crossed module of groups are introduced and some of their basic properties are established. In particular, we investigate some common properties between normal crossed modules and their tensor products, and present some bounds on the nilpotency class and solvability length of the...

Non-unitary Valuation Subalgebras