Results 1  10
of
10
Setoids in Type Theory
, 2000
"... Formalising mathematics in dependent type theory often requires to use setoids, i.e. types with an explicit equality relation, as a representation of sets. This paper surveys some possible denitions of setoids and assesses their suitability as a basis for developing mathematics. In particular, we ..."
Abstract

Cited by 42 (4 self)
 Add to MetaCart
Formalising mathematics in dependent type theory often requires to use setoids, i.e. types with an explicit equality relation, as a representation of sets. This paper surveys some possible denitions of setoids and assesses their suitability as a basis for developing mathematics. In particular, we argue that a commonly advocated approach to partial setoids is unsuitable, and more generally that total setoids seem better suited for formalising mathematics. 1
Restriction categories I: Categories of partial maps
 Theoretical Computer Science
, 2001
"... ..."
(Show Context)
Operads In HigherDimensional Category Theory
, 2004
"... The purpose of this paper is to set up a theory of generalized operads and multicategories and to use it as a language in which to propose a definition of weak ncategory. Included is a full explanation of why the proposed definition of ncategory is a reasonable one, and of what happens when n < ..."
Abstract

Cited by 32 (2 self)
 Add to MetaCart
The purpose of this paper is to set up a theory of generalized operads and multicategories and to use it as a language in which to propose a definition of weak ncategory. Included is a full explanation of why the proposed definition of ncategory is a reasonable one, and of what happens when n <= 2. Generalized operads and multicategories play other parts in higherdimensional algebra too, some of which are outlined here: for instance, they can be used to simplify the opetopic approach to ncategories expounded by Baez, Dolan and others, and are a natural language in which to discuss enrichment of categorical structures.
Normalization and the Yoneda Embedding
"... this paper we describe a new, categorical approach to normalization in typed  ..."
Abstract

Cited by 24 (3 self)
 Add to MetaCart
this paper we describe a new, categorical approach to normalization in typed 
Basic bicategories
 Eprint math.CT/9810017
, 1998
"... A concise guide to very basic bicategory theory, from the definition of a bicategory to the coherence theorem. ..."
Abstract

Cited by 19 (1 self)
 Add to MetaCart
A concise guide to very basic bicategory theory, from the definition of a bicategory to the coherence theorem.
Quotients of the multiplihedron as categorified associahedra
 Homotopy, Homology and Appl
, 2008
"... Abstract. We describe a new sequence of polytopes which characterize A ∞ maps from a topological monoid to an A ∞ space. Therefore each of these polytopes is a quotient of the corresponding multiplihedron. Our sequence of polytopes is demonstrated not to be combinatorially equivalent to the associah ..."
Abstract

Cited by 7 (2 self)
 Add to MetaCart
(Show Context)
Abstract. We describe a new sequence of polytopes which characterize A ∞ maps from a topological monoid to an A ∞ space. Therefore each of these polytopes is a quotient of the corresponding multiplihedron. Our sequence of polytopes is demonstrated not to be combinatorially equivalent to the associahedra, as was previously assumed in both topological and categorical literature. They are given the new collective name composihedra. We point out how these polytopes are used to parameterize compositions in the formulation of the theories of enriched bicategories and pseudomonoids in a monoidal bicategory. We also present a simple algorithm for determining the extremal points in Euclidean space whose convex hull is the nth polytope in the sequence of
The Extensive Completion Of A Distributive Category
 Theory Appl. Categ
, 2001
"... A category with finite products and finite coproducts is said to be distributive if the canonical map AB+AC # A (B +C) is invertible for all objects A, B, and C. Given a distributive category D , we describe a universal functor D # D ex preserving finite products and finite coproducts, for wh ..."
Abstract

Cited by 6 (1 self)
 Add to MetaCart
(Show Context)
A category with finite products and finite coproducts is said to be distributive if the canonical map AB+AC # A (B +C) is invertible for all objects A, B, and C. Given a distributive category D , we describe a universal functor D # D ex preserving finite products and finite coproducts, for which D ex is extensive; that is, for all objects A and B the functor D ex /A D ex /B # D ex /(A + B) is an equivalence of categories. As an application, we show that a distributive category D has a full distributive embedding into the product of an extensive category with products and a distributive preorder. 1.
The low dimensional structures that tricategories form
, 2007
"... We form tricategories and the homomorphisms between them into a bicategory. We then enrich this bicategory into an example of a threedimensional structure called a locally double bicategory, this being a bicategory enriched in the monoidal 2category of weak double categories. Finally, we show that ..."
Abstract

Cited by 3 (0 self)
 Add to MetaCart
(Show Context)
We form tricategories and the homomorphisms between them into a bicategory. We then enrich this bicategory into an example of a threedimensional structure called a locally double bicategory, this being a bicategory enriched in the monoidal 2category of weak double categories. Finally, we show that every sufficiently wellbehaved locally double bicategory gives rise to a tricategory, and thereby deduce the existence of a tricategory of tricategories.
Van Kampen theorems for toposes
"... In this paper we introduce the notion of an extensive 2category, to be thought of as a "2category of generalized spaces". We consider an extensive 2category K equipped with a binaryproductpreserving pseudofunctor C : K CAT, which we think of as specifying the "coverings&quo ..."
Abstract

Cited by 1 (0 self)
 Add to MetaCart
In this paper we introduce the notion of an extensive 2category, to be thought of as a "2category of generalized spaces". We consider an extensive 2category K equipped with a binaryproductpreserving pseudofunctor C : K CAT, which we think of as specifying the "coverings" of our generalized spaces. We prove, in this context, a van Kampen theorem which generalizes and refines one of Brown and Janelidze. The local properties required in this theorem are stated in terms of morphisms of effective descent for the pseudofunctor C . We specialize the general van Kampen theorem to the 2category Top S of toposes bounded over an elementary topos S , and to its full sub 2category LTop S determined by the locally connected toposes, after showing both of these 2categories to be extensive. We then consider three particular notions of coverings on toposes corresponding respectively to local homeomorphisms, covering projections, and unramified morphisms; in each case we deduce a suitable version of a van Kampen theorem in terms of coverings and, under further hypotheses, also one in terms of fundamental groupoids. An application is also given to knot groupoids and branched coverings. Along the way
THE EXTENSIVE COMPLETION OF A DISTRIBUTIVE CATEGORY J.R.B. COCKETT AND STEPHEN LACK
"... ABSTRACT. A category with finite products and finite coproducts is said to be distributive ifthe canonical map A × B + A × C → A × (B + C) is invertible for all objects A, B, andC. Given a distributive category D, we describe a universal functor D → Dex preserving finite products and finite coproduc ..."
Abstract
 Add to MetaCart
(Show Context)
ABSTRACT. A category with finite products and finite coproducts is said to be distributive ifthe canonical map A × B + A × C → A × (B + C) is invertible for all objects A, B, andC. Given a distributive category D, we describe a universal functor D → Dex preserving finite products and finite coproducts, for which Dex is extensive; thatis,for all objects A and B the functor Dex/A × Dex/B → Dex/(A + B) is an equivalence of categories.