Restricted Permutations by Patterns
نویسنده
چکیده
Recently, Babson and Steingrimsson (see [BS]) introduced generalized permutations patterns that allow the requirement that two adjacent letters in a pattern must be adjacent in the permutation. In this paper we study the generating functions for the number of permutations on n letters avoiding a generalized pattern ab-c where (a, b, c) ∈ S3, and containing a prescribed number of occurrences of generalized pattern cd-e where (c, d, e) ∈ S3. As a consequence, we derive all the previously known results for this kind of problems, as well as many new results.
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تاریخ انتشار 2002