The KP hierarchy, branched covers, and triangulations

Details The KP hierarchy, branched covers, and triangulations The KP hierarchy, branched covers, and triangulations

2008-03-27

arxiv.org/abs/0803.3980v1

Mathematics

Combinatorics

Scientific paper

The KP hierarchy is a completely integrable system of quadratic, partial differential equations that generalizes the KdV hierarchy. A linear combination of Schur functions is a solution to the KP hierarchy if and only if its coefficients satisfy the Plucker relations from geometry. We give a solution to the Plucker relations involving products of variables marking contents for a partition, and thus give a new proof of a content product solution to the KP hierarchy, previously given by Orlov and Shcherbin. In our main result, we specialize this content product solution to prove that the generating series for a general class of transitive ordered factorizations in the symmetric group satisfies the KP hierarchy. These factorizations appear in geometry as encodings of branched covers, and thus by specializing our transitive factorization result, we are able to prove that the generating series for two classes of branched covers satisfies the KP hierarchy. For the first of these, the double Hurwitz series, this result has been previously given by Okounkov. The second of these, that we call the m-hypermap series, contains the double Hurwitz series polynomially, as the leading coefficient in m. The m-hypermap series also specializes further, first to the series for hypermaps and then to the series for maps, both in an orientable surface. For the latter series, we apply one of the KP equations to obtain a new and remarkably simple recurrence for triangulations in a surface of given genus, with a given number of faces. This recurrence leads to explicit asymptotics for the number of triangulations with given genus and number of faces, in recent work by Bender, Gao and Richmond.

Affiliated with

Also associated with

No associations

Rating

The KP hierarchy, branched covers, and triangulations does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The KP hierarchy, branched covers, and triangulations, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The KP hierarchy, branched covers, and triangulations will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-354399