# Contents

## Definition

Cobase change is another term for pushout of a morphism:

if

$\array{ X &\to & U \\ \downarrow && \downarrow \\ Y &\to& Y \sqcup_X U }$

is a pushout square in some category then the morphism $U \to U \sqcup_X Y$ is the cobase change or cobase extension of $X \to Y$ along $X \to U$.

## Remarks

Revised on May 19, 2010 09:09:08 by Urs Schreiber (131.211.232.167)