A statistic on involutions
DSpace at IIT Bombay
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Title |
A statistic on involutions
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Creator |
DEODHAR, RS
SRINIVASAN, MK |
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Subject |
finite vector-spaces
formula permutation statistics q-binomial coefficient bruhat order involutions fixed point free involutions |
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Description |
We define a statistic, called weight, on involutions and consider two applications in which this statistic arises. Let I(n) denote the set of all involutions on [n](={1,2,..., n}) and let F(2n) denote the set of all fixed point free involutions on [2n]. For an involution delta, let \ delta \ denote the number of 2-cycles in delta. Let [n](q)=1+q+...+q(n-1) and let ((n)(k))(q) denote the q-binomial coefficient. There is a statistic wt on I(n) such that the following results are true. (i) We have the expansion [GRAPHICS] (ii) An analog of the (strong) Bruhat order on permutations is defined on F(2n) and it is shown that this gives a rank-2((n)(2)) graded EL-shellable poset whose order complex triangulates a ball. The rank of delta is an element ofF(2n) is given by wt(delta) and the rank generating function is [1](q)[3](q)...[2n-1](q).
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Publisher |
KLUWER ACADEMIC PUBL
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Date |
2011-08-17T03:07:00Z
2011-12-26T12:55:18Z 2011-12-27T05:44:04Z 2011-08-17T03:07:00Z 2011-12-26T12:55:18Z 2011-12-27T05:44:04Z 2001 |
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Type |
Article
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Identifier |
JOURNAL OF ALGEBRAIC COMBINATORICS, 13(2), 187-198
0925-9899 http://dx.doi.org/10.1023/A:1011249732234 http://dspace.library.iitb.ac.in/xmlui/handle/10054/9719 http://hdl.handle.net/10054/9719 |
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Language |
en
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