DEPARTMENT OF MATHEMATICS
       ALGEBRA AND COMBINATORICS SEMINAR

   THURSDAY 29 JULY 2004, 12 noon in Room 67-641


       Not all numbers were created equal

                 Ian Wanless
     Department of Computer Science, ANU


Abstract
In three recent and seemingly unrelated combinatorial enumerations
the author has uncovered a strikingly similar property of the results;
a suspiciously high power of 2 lurking amongst the factors. These
observations can only be partly predicted by theoretic means.

The three enumerations in question are the latin squares
of orders up to 11, the permanents of Hadamard matrices of orders up to 28
and the orthomorphisms in groups of order up to 19.

The first of these was the most technically challenging, and was achieved
by means of counting 1-factorisations of bipartite graphs.

The big question remains: "Could these three calculations be related at
some deeper level?"


All welcome.