[Nauty-list] Difficult concept

[Roger Ting]

After corresponding with two people (Edward Turner and Noah 
Giansiracusa) who had studied Nauty before, i found that all of us had 
not been able to grasp the concept of indicator function. It will be 
great that  Brendan can respond to this by providing a layman version of 
the paper or a more simpler explanation of indicator function or even a 
simple example of how exactly  Nauty select a terminal node to  become  
the canonical label. This can help everyone a lot and probably bring 
some improvement to the algorithm. Thanks.