منابع مشابه
The Möbius function of permutations with an indecomposable lower bound
We show that the Möbius function of an interval in a permutation poset where the lower bound is sum (resp. skew) indecomposable depends solely on the sum (resp. skew) indecomposable permutations contained in the upper bound, and that this can simplify the calculation of the Möbius sum. For increasing oscillations, we give a recursion for the Möbius sum which only involves evaluating simple ineq...
متن کاملIndecomposable permutations with a given number of cycles
A permutation a1a2 . . . an is indecomposable if there does not exist p < n such that a1a2 . . . ap is a permutation of {1, 2, . . . , p}. We compute the asymptotic probability that a permutation of Sn with m cycles is indecomposable as n goes to infinity with m/n fixed. The error term is O( log(n−m) n−m ). The asymptotic probability is monotone in m/n, and there is no threshold phenomenon: it ...
متن کاملNumber of right ideals and a q-analogue of indecomposable permutations
We prove that the number of right ideals of codimension n in the algebra of noncommutative Laurent polynomials in two variables over the finite field Fq is equal to (q − 1)q (n+1)(n−2) 2 ∑ θ q , where the sum is over all indecomposable permutations in Sn+1 and where inv(θ) stands for the number of inversions of θ. Mathematics Subject Classification Numbers: Primary: 05A15, Secondary: 05A19 Date...
متن کاملOn the Number of Indecomposable Permutations with a Given Number of Cycles
Abstract. A permutation a1a2 . . . an is indecomposable if there does not exist p < n such that a1a2 . . . ap is a permutation of {1, 2, . . . , p}. We consider the probability that a permutation of Sn with m cycles is indecomposable and prove that this probability is monotone non-increasing in n. We compute also the asymptotic probability when n goes to infinity with m/n tending to a fixed rat...
متن کاملPartial Duality of Hypermaps
We introduce a collection of new operations on hypermaps, partial duality, which include the classical Euler-Poincaré dualities as particular cases. These operations generalize the partial duality for maps, or ribbon graphs, recently discovered in a connection with knot theory. Partial duality is different from previous studied operations of S. Wilson, G. Jones, L. James, and A. Vince. Combinat...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: European Journal of Combinatorics
سال: 2009
ISSN: 0195-6698
DOI: 10.1016/j.ejc.2008.04.002