An elementary illustrated introduction to simplicial sets
G. Friedman. (2008)cite http://arxiv.org/abs/0809.4221arxiv:0809.4221Comment: 57 pages, 32 figures. Further corrections and additions. Section 2 has been reorganized with new material added. Section 5.1 on Simplicial Hom added. Hopefully final version.
This is an expository introduction to simplicial sets and simplicial homotopy
theory with particular focus on relating the combinatorial aspects of the
theory to their geometric/topological origins. It is intended to be accessible
to students familiar with just the fundamentals of algebraic topology.