Fig. 42.
Converting a pair of odd faces to even ones. Circles indicate the initial vertices of the faces and crosses mark those vertices that had been added to obtain faces with an even number of vertices
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.