摘要
Let Dn be the set of all signed permutations on n = {1,...,n} with even signs,and let Dn(T) be the set of all signed permutations in Dn which avoids a set T of signed patterns.In this paper,we find all the cardinalities of the sets Dn(T) where T■B2.Some of the cardinalities encountered involve inverse binomial coefficients,binomial coefficients,Catalan numbers,and Fibonacci numbers.
Let Dn be the set of all signed permutations on [n] = {1,... ,n} with even signs, and let ：Dn（T） be the set of all signed permutations in Dn which avoids a set T of signed patterns. In this paper, we find all the cardinalities of the sets Dn（T） where T B2. Some of the cardinalities encountered involve inverse binomial coefficients, binomial coefficients, Catalan numbers, and Fibonacci numbers.
基金
The National Natural Science Foundation of China （No. 10801020）.
