Counting $1324$, $4231$-Avoiding Permutations
نویسندگان
چکیده
منابع مشابه
Counting 1324, 4231-Avoiding Permutations
Classes of permutations are sets of permutations that are closed downwards under taking subpermutations. They are usually presented as sets C that avoid a given set B of permutations (i.e. the permutations of C have no subpermutation in the set B). We express this by the notation C = Av(B). Much of the inspiration for elucidating the structure of pattern classes has been driven by the enumerati...
متن کاملCounting 1324-Avoiding Permutations
We consider permutations that avoid the pattern 1324. By studying the generating tree for such permutations, we obtain a recurrence formula for their number. A computer program provides data for the number of 1324-avoiding permutations of length up to 20.
متن کاملA New Record for 1324-avoiding Permutations
We prove that the class of 1324-avoiding permutations has exponential growth rate at most 13.74. To Richard Stanley, on the occasion of his seventieth birthday.
متن کاملoutputs Permutations avoiding 1324 and patterns in
The class Av(1324), of permutations avoiding the pattern 1324, is one of the simplest sets of combinatorial objects to define that has, thus far, failed to reveal its enumerative secrets. By considering certain large subsets of the class, which consist of permutations with a particularly regular structure, we prove that the growth rate of the class exceeds 9.81. This improves on a previous lowe...
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We enumerate the pattern class Av(2143, 4231) and completely describe its permutations. The main tools are simple permutations and monotone grid classes.
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ژورنال
عنوان ژورنال: The Electronic Journal of Combinatorics
سال: 2009
ISSN: 1077-8926
DOI: 10.37236/225