Given a collection C of subsets of a finite set X, let S C = ∪S∈CS. Philip Hall’s celebrated theorem [2] concerning ‘systems of distinct representatives’ tells us that for any collection C of subsets of X there exists an injective (i.e. one-to-one) function f : C → X with f(S) ∈ S for all S ∈ C if and and only if C satisfies the property that for all non-empty subsets C ′ of C we have | S C | ≥...

I discuss the general formalism of two-dimensional topological field theories defined on open-closed oriented Riemann surfaces, starting from an extension of Segal’s geometric axioms. Exploiting the topological sewing constraints allows for the identification of the algebraic structure governing such systems. I give a careful treatment of bulk-boundary and boundary-bulk correspondences, which a...

In this paper, we study injective and nuclear real W*- C*-algebras. The connection of these concepts with similar enveloping C*-algebras is considered. equivalence the injectivity nuclearity for shown. As a consequence, factors types II1, II, III1, III0 III (0 1) are completely described.

We prove that the crossed product C∗-algebra C∗ r (Γ, ∂Γ) of a free group Γ with its boundary ∂Γ naturally sits between the reduced group C∗algebra C∗ r Γ and its injective envelope I(C∗ r Γ). In other words, we have natural inclusion C∗ r Γ ⊂ C∗ r (Γ, ∂Γ) ⊂ I(C∗ r Γ) of C∗-algebras.

The structure of the group Aut(Cn) of biholomorphisms of Cn is largely unknown if n > 1. In stark contrast Aut(C) is rather small, consisting of the nonconstant affine linear maps. The description of Aut(C) follows from the observation that an injective holomorphic function f : C → C satisfying f(0) = 0 and f ′(0) = 1 must be the identity. These considerations suggest that similar characterizat...

Auslander’s formula shows that any abelian category C is equivalent to the category of coherent functors on C modulo the Serre subcategory of all effaceable functors. We establish a derived version of this equivalence. This amounts to showing that the homotopy category of injective objects of some appropriate Grothendieck abelian category (the category of ind-objects of C) is compactly generate...

We study localizing and colocalizing subcategories of a comodule category of a coalgebra C over a field, using the correspondence between localizing subcategories and equivalence classes of idempotent elements in the dual algebra C∗. In this framework, we give a useful description of the localization functor by means of the Morita–Takeuchi context defined by the quasi-finite injective cogenerat...

A semi-dualizing module over a commutative noetherian ringA is a finitely generated module C with RHomA(C,C) ≃ A in the derived category D(A). We show how each such module gives rise to three new homological dimensions which we call C–Gorenstein projective, C–Gorenstein injective, and C–Gorenstein flat dimension, and investigate the properties of these dimensions.

In this paper, we first present a new type of the concept of open sets by expressing some properties of arbitrary mappings on a power set. With the generalization of the closure spaces in categorical topology, we introduce the generalized topological spaces and the concept of generalized continuity and become familiar with weak and strong structures for generalized topological spaces. Then, int...

Abstract Assume that k is an algebraically closed field and A a finite-dimensional wild -algebra. Recently, L. Gregory M. Prest proved in this case the width of lattice all pointed -modules undefined. Hence result Ziegler implies there exists super-decomposable pure-injective -module, if base countable. Here we give different straightforward proof fact. Namely, show special family -modules, cal...