Forbidden subsequences
نویسندگان
چکیده
منابع مشابه
Generating trees and forbidden subsequences
We discuss an enumerative technique called generating frees which was introduced in the study of Baxter permutations. We apply the technique to some other classes of permutations with forbidden subsequences. We rederive some known results, e.g. ]S,(132,231)[ = 2” and l&,(123,132,213)1 = F,, and add several new ones: &(123,3241), S,(123,3214),8,(123,2143). Finally, we argue for the broader use o...
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In (West, Discrete Math. 157 (1996) 363-374) it was shown using transfer matrices that the number [Sn(123; 3214)1 of permutations avoiding the pattems 123 and 3214 is the Fibonacci number F2, (as are also IS,(213; 1234)1 and 1S~(213;4123)1 ). We now find the transfer matrix for IS , (123;r , r 1 . . . . . 2,1,r + 1)1, IS,(213;1,2 . . . . . r , r + 1)1, and ISn(213;r + 1,1,2 . . . . . r)l, deter...
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A permutation avoids the subpattern i3 has no subsequence having all the same pairwise comparisons as , and we write ∈ S( ). We examine the classes of permutations, S(321); S(321; 37 142) and S(4231; 4132), enumerated, respectively by the famous Catalan, Motzkin and Schr; oder number sequences. We determine their generating functions according to their length, number of active sites and inversi...
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ژورنال
عنوان ژورنال: Discrete Mathematics
سال: 1994
ISSN: 0012-365X
DOI: 10.1016/0012-365x(94)90242-9