Let C be a unital AH-algebra and let A be a unital separable simple C-algebra with tracial rank no more than one. Suppose that φ, ψ : C → A are two unital monomorphisms. With some restriction on C, we show that φ and ψ are approximately unitarily equivalent if and only if [φ] = [ψ] in KL(C,A) τ ◦ φ = τ ◦ ψ for all tracial states of A and φ = ψ, where φ and ψ are homomorphisms from U0(C)/CU(C) →...

Let Uβ be the special Buekenhout-Metz unital in PG(2, q 2) formed by a union of q conics, where q = pe is an odd prime power. It can be shown that the dimension of the binary code of the corresponding unital design Uβ is less than or equal to q3 + 1− q. Baker and Wantz conjectured that equality holds. We prove that the aforementioned dimension is greater than or equal to q3(1− 1 p ) + q 2 p .

Let A be a unital simple AT-algebra of real rank zero. Given an isomorphism γ1 : K1(A)→ K1(A), we show that there is an automorphism α : A → A such that α∗1 = γ1 which has the tracial Rokhlin property. Consequently, the crossed product A ⋊α Z is a simple unital AH-algebra with real rank zero. We also show that automorphism with Rokhlin property can be constructed from minimal homeomorphisms on ...

Abstract. We define a BV-structure on the Hochschild-cohomology of a unital, associative algebra A with a symmetric, invariant and non-degenerate inner product. The induced Gerstenhaber algebra is the one described in Gerstenhaber’s original paper on Hochschild-cohomology. We also prove the corresponding theorem in the homotopy case, namely we define the BV-structure on the Hochschild-cohomolog...

Unless we say otherwise, every vector space we talk about is taken to be over C. A Banach algebra is a Banach space A that is also an algebra satisfying ‖AB‖ ≤ ‖A‖ ‖B‖ for A,B ∈ A. We say that A is unital if there is a nonzero element I ∈ A such that AI = A and IA = A for all A ∈ A, called a identity element. If X is a Banach space, let B(X) denote the set of bounded linear operators X → X, and...

In this paper, we introduce a general theory of corner rings in noncommutative rings that generalizes the classical notion of Peirce decompositions with respect to idempotents. Two basic types of corners are the Peirce corners eRe (e2 = e) and the unital corners (corners containing the identity of R). A general corner is both a unital corner of a Peirce corner, and a Peirce corner of a unital c...

We give a general construction for unitals of order q admitting an action of SU(2, q). The construction covers the classical hermitian unitals, Grüning’s unitals in Hall planes and at least one unital of order four where the translation centers fill precisely one block. For the latter unital, we determine the full group of automorphisms and show that there are no group-preserving embeddings int...

We give a classification theorem for unital separable nuclear simple C∗-algebras with tracial rank no more than one. Let A and B be two unital separable simple nuclear C∗-algebras with TR(A), TR(B) ≤ 1 which satisfy the universal coefficient theorem. We show that A ∼= B if and only if (K0(A),K0(A)+, [1A], K1(A), T (A)) ∼= (K0(B), K0(B)+, [1B ], K1(B), T (B)).

Let U be a known unital of PG(2, q), q odd, and let N be a t-nest in a regular spread S. Suppose we replace N by a replacement set N̂ to form the new spread S ′ = (S\N)∪ N̂ ). Using the Bruck-Bose correspondence, we look at the affine points of U in P(S) ∼= PG(2, q) and see whether the corresponding affine point set in the new plane P(S ′) can be completed to a unital.

We show that if T is an isometry (as metric spaces) from an open subgroup of the group of the invertible elements in a unital semisimple commutative Banach algebra onto an open subgroup of the group of the invertible elements in a unital Banach algebra, then T (1)T is an isometrical group isomorphism. In particular, T (1)T is extended to an isometrical real algebra isomorphism from A onto B.