Issue Information
روزنامه با شماره پیاپی سال 1995
Pages
58
From page
131
To page
188
Abstract
Using the Makkaiʹs duality for first-order logic, we characterise effective descent morphisms in 2-categories of pretoposes and Barr-exact categories. In both cases they coincide with conservative morphisms. We show that in those 2-categories the 2-coregular factorisations are exactly quotient-conservative factorisations. We also prove a generalisation of the Makkai duality for pseudoelementary categories.
Journal title
Annals of Pure and Applied Logic
Serial Year
1995
Journal title
Annals of Pure and Applied Logic
Record number
889983
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