Coloured Permutations Containing and Avoiding Certain Patterns

被引:0
|
作者
Toufik Mansour
机构
[1] Chalmers University of Technology,Department of Mathematics
关键词
alternating permutations; restricted permutations; generating functions; Chebyshev polynomials;
D O I
10.1007/s00026-003-0190-2
中图分类号
学科分类号
摘要
Let \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$ s^{(r)}_{n} $$ \end{document} be the set of all coloured permutations on the symbols 1, 2, . . . , n with colours 1, 2, . . . , r, which is the analogous of the symmetric group when r = 1, and the hyperoctahedral group when r = 2. Let \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$ I \subseteq \{1,2,\ldots,r\} $$ \end{document} be a subset of d colours; we define \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$ T_{k,r}^m (l) $$ \end{document} to be the set of all coloured permutations \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$ \Phi \in S_{k}^{(r)} \quad \mathrm{such\quad that}\quad \Phi_1 = M^{(c)} \quad \mathrm{where}\quad c \in I$$ \end{document}. We prove that the number of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$ T_{k,r}^{m} (l) $$ \end{document} -avoiding coloured permutations in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$ S_{n}^{(r)} \quad \mathrm{equals}\quad (k-1)!r^{k-1} \prod_{j=k}^n h_j \quad \mathrm{for}\quad n\geq k \quad \mathrm{where} \quad h_j = (r-d) j+(k-1)d $$ \end{document}. We then prove that for any \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$ \Phi \in T_{k,r}^{1} (I) \quad(\mathrm{or \quad any}\quad \Phi \in T_{k,r}^{k} (I)) $$ \end{document}, the number of coloured permutations in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$ S-{n}^{(r)} $$ \end{document} which avoid all patterns in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$ T_{k,r}^{1} (I) \quad(\mathrm{or \quad in}\quad T_{k,r}^{k} (I)) $$ \end{document} except for Φ and contain Φ exactly once equals \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$ \prod_{j=k}^n h_j \cdot \sum_{j=k}^{n} \frac{1}{hj \quad} \mathrm{for}\quad n \geq k $$ \end{document}. Finally, for any \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$ \Phi \in T_{k,r}^{m} (I), 2\leq m \leq k-1 $$ \end{document}, this number equals \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$ \prod_{j=k+1}^{n} h_j \quad \mathrm{for} \quad n\geq k+1 $$ \end{document}. These results generalize recent results due to Mansour, Mansour and West, and Simion.
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页码:349 / 355
页数:6
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