Permanents and determinants of (0,1) matrices

[Gordon Royle]

> I haven't worked this through fully and checked it by implementing it, but
> it seems clear to me (at the moment) that if the automorphism group of the

Blah blah... Brendan just pointed out that I should have worked it through
fully before shooting my mouth off b/c it is easy to see that half/half is
the only situation that can occur for non-singular matrices...