Combinatorics at UCD

Fremen

Right, here's a long shot:

As an undergrad, I took a combinatorics course in UCD taught by Thomas Laffey. I'm just wondering if there's anyone else out there who has taken that course, since I'm trying to remember the name of a theorem we proved.

The proof put a bound on the size of the Permanent of a matrix(that's the determinant without the "minus" signs, loosely speaking). Laffey described it as a "Black magic" proof, since it uses a lot of steps which don't seem like they would lead to a proof, yet after a very convoluted argument, somehow they do.

I think it could be related to the van der warden conjecture, but looking that up, nothing rings a bell. If you took the class, you'd remember this proof, it was pretty freaky. I think Laffey described it as "one of the hardest proofs in modern maths".

LeixlipRed

"one of the hardest proofs in modern maths" in an undergrad course? Cool

Fremen

Didn't seem cool at the time...

thebaldsoprano

Apologies for dragging up an old thread, just wondering did you have any luck with this OP? Proofs involving black magic, witchcraft etc always make for interesting reading

I did some digging around but came up empty...

timbrophy

Have a look at http://mathworld.wolfram.com/Permanent.html
which might help.

RoundTower

I took the course - I vaguely remember him saying something like that but your description of the proof doesn't ring a bell

Fremen

It was Bregman's theorem on permanents, he gave a version by Schrijver. I gave up and mailed him in the end.

Wow, old thread!