New York City Category Theory Seminar
Something Old, Something New, Something Borrowed, ...
Next F.E.J. Linton • Wesleyan Univ. Math/CS Emeritus

Two triangles Begin with two triangles.

Topology as usual except for the southernmost vertices, whose smallish basic neighborhoods are “broken Vs” ...
Single Triangle
Here (depicted in red) is a typical one for one of those vertices ...