Montreal Geometric & Combinatorial Group Theory Seminar
 
 
Speaker: Dani 
Wise (McGill) 
Title: “Honeycombs 
and tori in C(6) 2-complexes”
Date: 3:30pm 
Wednesday, February 19th. 
Room: 920 
Burnside
Abstract:  
 
The familiar 
“honeycomb” hexagonal tessellation of the plane generalizes to the notion of a 
“C(6) 2-complex” which has the property that a path traveling around a 2-cell 
passes through at least 6 neighboring 2-cells. 
 
Let X be a 
compact C(6) complex. It is not hard to show that p1X fails to be word-hyperbolic if and only if 
X contains a honeycomb in its universal cover. Furthermore there is a 
“periodic honeycomb” if and only if  
Z´Z is a subgroup of p1X.
 
The question is: 
Does the universal cover of X contain a honeycomb if and only if it contains 
a periodic honeycomb?
 
I suspect the answer is yes, and I will describe some partial results.