Sommaire du Fascicule no. 1

International category theory meeting. Bangor, Wales, july 2-7 1989. Cambridge, England, march 23-25, 1990
More on graphic toposes
Combinatorial-geometric aspects of polycategory theory : pasting schemes and higher Bruhat orders (list of results)
∞-groupoids and homotopy types
A 2-categorical approach to change of base and geometric morphisms I

Sommaire du Fascicule no. 2

The frame of fibrewise closed nuclei
The exact sequence in the homology of groups with integral coefficients modulo q associated to two normal subgroups
Almost smooth algebras
Monads and cocompleteness of categories
Presentations of étendues
Indexed categories for program development

Sommaire du Fascicule no. 3

What is a double central extension ? (the question was asked by Ronald Brown)
The connection between the fundamental groupoid and a unification algorithm for syntactil algebras (extended abstract)
On Priestley duals of products
Strong regular and dense generators

Sommaire du Fascicule no. 4

Catégorie algébriques prégaloisiennes
ϰ-Lindelöf locales and their spatial parts
Parity complexes
Counting measure for Kuratowski finite parts and decidability