We extend the notion of consecutive pattern avoidance to considering sums over all permutations where each term is a product of weights depending on each consecutive pattern of a fixed length. We study the problem of finding the asymptotics of these sums. Our technique is to extend the spectral method of Ehrenborg, Kitaev and Perry. When the weight depends on the descent pattern we show how to find the equation determining the spectrum. We give two length 4 applications. First, we find the asymptotics of the number of permutations with no triple ascents and no triple descents. Second, we give the asymptotics of the number of permutations with no isolated ascents or descents. Our next result is a weighted pattern of length 3 where the associated operator only has one non-zero eigenvalue. Using generating functions we show that the error term in the asymptotic expression is the smallest possible.
|Number of pages||16|
|Journal||Advances in Applied Mathematics|
|State||Published - Sep 2012|
Bibliographical noteFunding Information:
The authors thank Margaret Readdy and the two referees for their comments on an earlier draft of this paper. The authors are partially funded by the National Science Foundation grant DMS-0902063. The first author also thanks the Institute for Advanced Study and is also partially supported by the National Science Foundation grants DMS-0835373 and CCF-0832797.
- Asymptotic expansions
- Integral operators
- Weighted consecutive pattern avoidance
ASJC Scopus subject areas
- Applied Mathematics