Z-Hyperrigidity and Z-boundary representations

Lifting Representations of Z - Groups

Let K be the kernel of an epimorphism G→ Z, where G is a finitely presented group. If K has infinitely many subgroups of index 2, 3 or 4, then it has uncountably many. Moreover, if K is the commutator subgroup of a classical knot group G, then any homomorphism from K onto the symmetric group S2 (resp. Z3) lifts to a homomorphism onto S3 (resp. alternating group A4).

Automated Boundary Testing from Z and B

Commutativity degree of $mathbb{Z}_p$≀$mathbb{Z}_{p^n}

For a nite group G the commutativity degree denote by d(G) and dend:$$d(G) =frac{|{(x; y)|x, yin G,xy = yx}|}{|G|^2}.$$ In [2] authors found commutativity degree for some groups,in this paper we nd commutativity degree for a class of groups that have high nilpontencies.

The Noncommutative Choquet Boundary Ii: Hyperrigidity

A (finite or countably infinite) set G of generators of an abstract C∗-algebra A is called hyperrigid if for every faithful representation of A on a Hilbert space A ⊆ B(H) and every sequence of unital completely positive linear maps φ1, φ2, . . . from B(H) to itself, lim n→∞ ‖φn(g)− g‖ = 0,∀g ∈ G =⇒ lim n→∞ ‖φn(a)− a‖ = 0, ∀a ∈ A. We show that one can determine whether a given set G of generato...

Z Z N -quasialgebras

Recently we have reformulated the octonions as quasissociative algebras (quasialgebras) living in a symmetric monoidal category. In this note we provide further examples of quasialgebras, namely ones where the nonassociativity is induced by a Z Z n-grading and a nontrivial 3-cocycle.