Tutte Colloquium - Ahmad Abdi

Friday, July 24, 2015 3:30 pm - 3:30 pm EDT (GMT -04:00)

Title:  When is the set covering polyhedron integral?

Speaker: Ahmad Abdi
Affiliation: University of Waterloo
Room: MC 5501

Abstract:  A 0,1 matrix is perfect if its set packing polyhedron is
integral, and it is ideal if its set covering polyhedron is integral. The
Strong Perfect Graph Theorem provides a characterization of perfect
matrices. Is there such a characterization of ideal matrices? So far, there
has not been any...

In 1976, Seymour proved that a 0,1 matrix is either so-called binary or it
is very fragile and close to being non-ideal. A year later, he conjectured
a characterization for binary matrices that are ideal; his conjecture is
now known as the f-Flowing Conjecture. Guenin and I have been working on this conjecture for the past couple of years; I will report on our progress so far.

As far as I know, there is no road map for characterizing when non-binary
matrices are ideal. I will talk about some tools developed in joint work
with Fukasawa and Sanità, and in joint work with Pashkovich, that I think
will help in this direction.