Signed Involutions Avoiding 2-letter Signed Patterns
نویسندگان
چکیده
Let In be the class of all signed involutions in the hyperoctahedral group Bn and let In(T ) be the set of involutions in In which avoid a set T of signed patterns. In this paper, we complete a further case of the program initiated by Simion and Schmidt [6] by enumerating In(T ) for all signed permutations T ⊆ B2.
منابع مشابه
New Equivalences for Pattern Avoiding Involutions
We complete the Wilf classification of signed patterns of length 5 for both signed permutations and signed involutions. New general equivalences of patterns are given which prove Jaggard’s conjectures concerning involutions in the symmetric group avoiding certain patterns of length 5 and 6. In this way, we also complete the Wilf classification of S5, S6, and S7 for involutions.
متن کاملNew Equivalences for Pattern Avoidance for Involutions
We complete the Wilf classification of signed patterns of length 5 for both signed permutations and signed involutions. New general equivalences of patterns are given which prove Jaggard’s conjectures concerning involutions in the symmetric group avoiding certain patterns of length 5 and 6. In this way, we also complete the Wilf classification of S5, S6, and S7 for both permutations and involut...
متن کاملRestricted Single or Double Signed Patterns
Let E n = {[τ ]a = (τ (a1) 1 , . . . , τ (an) n )|τ ∈ Sn, 1 ≤ ai ≤ r} be the set of all signed permutations on the symbols 1, 2, . . . , n with signs 1, 2, . . . , r. We prove, for every 2-letter signed pattern [τ ]a, that the number of [τ ]a-avoiding signed permutations in E n is given by the formula n ∑ j=0 j!(r−1) ( n j 2 . Also we prove that there are only one Wilf class for r = 1, four Wil...
متن کاملWilf classification of three and four letter signed patterns
We give some new Wilf equivalences for signed patterns which allow the complete classification of signed patterns of lengths three and four. The problem is considered for pattern avoidance by general as well as involutive signed permutations.
متن کاملTwo Involutions for Signed Excedance Numbers
Two involutions on permutations and derangements are constructed. They lead to a direct evaluation of some signed Eulerian polynomials on permutations and derangements. The latter formulas, combined with the exponential formula, give a new derivation of the corresponding generating functions.
متن کامل