The other pullback lemma
Category Theory
2014-10-07 v2
Abstract
Given a composition of two commutative squares, one well-known pullback lemma says that if both squares are pullbacks, then their composition is also a pullback; another well-known pullback lemma says that if the composed square is a pullback and the supporting square is a pullback, then the other square is a pullback as well. This note investigates the third of the possibilities.
Cite
@article{arxiv.1311.2974,
title = {The other pullback lemma},
author = {Michal R. Przybylek},
journal= {arXiv preprint arXiv:1311.2974},
year = {2014}
}