منابع مشابه
Sorted and or sortable permutations
In his Ph D thesis Julian West studied in depth a map that acts on permutations of the symmetric group Sn by partially sorting them through a stack The main motivation of this paper is to characterize and count the permutations of Sn which we call sorted permutations This is equivalent to counting preorders of increasing binary trees We rst nd a local characterization of sorted permutations The...
متن کامل2-stack Pushall Sortable Permutations
In the 60’s, Knuth introduced stack-sorting and serial compositions of stacks. In particular, one significant question arise out of the work of Knuth: how to decide efficiently if a given permutation is sortable with 2 stacks in series? Whether this problem is polynomial or NP-complete is still unanswered yet. In this article we introduce 2-stack pushall permutations which form a subclass of 2-...
متن کاملGeneralizations of Two-stack-sortable Permutations
i iii Acknowledgment My deepest gratitude goes to my advisor, Ira Gessel, without whom this work would not be possible; I would like to thank him for his generosity in sharing his insight and time with me, and his constant patience and encouragement. It was and will always be my pleasure to work with him.
متن کاملPermutations sortable by two stacks in series
We address the problem of the number of permutations that can be sorted by two stacks in series. We do this by first counting all such permutations of length less than 20 exactly, then using a numerical technique to obtain nineteen further coefficients approximately. Analysing these coefficients by a variety of methods we conclude that the OGF behaves as S(z) ∼ A(1− μ · z) , where μ = 12.45± 0....
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: Discrete Mathematics
سال: 2000
ISSN: 0012-365X
DOI: 10.1016/s0012-365x(00)00146-1