Tag Archives: integer sequences

9,21,27,45,81,153,…

Posted on 16/10/2014 by Peter Cameron

This is the sequence of degrees of primitive groups which don’t synchronize a map of rank 3, equivalently graphs with clique number and chromatic number 3 having primitive automorphism groups. You could argue that the sequence should start with 3, … Continue reading →

Posted in doing mathematics, open problems | Tagged , , , , , | 2 Comments

The ADE affair, 3

Posted on 23/06/2011 by Peter Cameron

Clusters, and the associated cluster algebras and cluster categories, form a hot topic in mathematics at the moment. Clusters are connected with topics such as Poisson geometry, integrable systems, representation theory and total positivity as well as combinatorial enumeration. I … Continue reading →

Posted in exposition, open problems | Tagged , , , , , | 1 Comment