中文

Refined Restricted Involutions

组合数学 2007-05-23 v1

摘要

Define Ink(α)I_n^k(\alpha) to be the set of involutions of {1,2,...,n}\{1,2,...,n\} with exactly kk fixed points which avoid the pattern αSi\alpha \in S_i, for some i2i \geq 2, and define Ink(;α)I_n^k(\emptyset;\alpha) to be the set of involutions of {1,2,...,n}\{1,2,...,n\} with exactly kk fixed points which contain the pattern αSi\alpha \in S_i, for some i2i \geq 2, exactly once. Let ink(α)i_n^k(\alpha) be the number of elements in Ink(α)I_n^k(\alpha) and let ink(;α)i_n^k(\emptyset;\alpha) be the number of elements in Ink(;α)I_n^k(\emptyset;\alpha). We investigate Ink(α)I_n^k(\alpha) and Ink(;α)I_n^k(\emptyset;\alpha) for all αS3\alpha \in S_3. In particular, we show that ink(132)=ink(213)=ink(321)i_n^k(132)=i_n^k(213)=i_n^k(321), ink(231)=ink(312)i_n^k(231)=i_n^k(312), ink(;132)=ink(;213)i_n^k(\emptyset;132) =i_n^k(\emptyset;213), and ink(;231)=ink(;312)i_n^k(\emptyset;231)=i_n^k(\emptyset;312) for all 0kn0 \leq k \leq n.

关键词

引用

@article{arxiv.math/0212267,
  title  = {Refined Restricted Involutions},
  author = {Emeric Deutsch and Aaron Robertson and Dan Saracino},
  journal= {arXiv preprint arXiv:math/0212267},
  year   = {2007}
}

备注

20 pages