Last year we saw the resolution of the Strong Perfect Graph
Conjecture, a major result in graph
theory. The conjecture stated that a graph is perfect if
and only if it does not contain an induced
subgraph H such that H or its complement is an odd cycle of length
at least five. Chudnovsky, Robertson, Seymour, and Thomas proved the
conjecture (now called the Strong Perfect Graph Theorem) last spring.
Vašek Chvátal has a
web
page describing this result.
Why am I mentioning this result here? The problem of testing whether a
graph is perfect in polynomial-time remained open even after this
theorem as neither characterization gives an obvious
algorithm. I just saw the the
abstract of a talk that Paul Seymour will give at the Institute of
Advanced Study next week. There he claims he and Chudnovsky have found
a polynomial-time algorithm for testing whether a graph is perfect. I
cannot find more about the algorithm on the web and I will miss the
talk at the institute. I will post more information about this
exciting new development when I have more details.