학술논문

Enumeration of walks in the square lattice according to their areas.
Document Type
Journal
Author
Mohammad-Noori, M. (IR-TEH-MSC) AMS Author Profile
Source
Journal of Combinatorial Mathematics and Combinatorial Computing (J. Combin. Math. Combin. Comput.) (20140101), 91, 257-274. ISSN: 0835-3026 (print).eISSN: 2817-576X.
Subject
05 Combinatorics -- 05A Enumerative combinatorics
  05A15 Exact enumeration problems, generating functions
Language
English
Abstract
Summary: ``We study the area distribution of closed walks of length$n$, starting and ending at the origin. The concept of algebraic areaof a walk in the square lattice is slightly modified and the usefulnessof this concept is demonstrated through a simple argument. The idea ofusing a generating function of the form $(x+x^{-1}+y+y^{-1})^n$ tostudy these walks is then discussed from a special viewpoint. Based onthis, a polynomial time algorithm for calculating the exactdistribution of such walks for a given length, is concluded. Thepresented algorithm takes advantage of the Chinese remainder theorem toovercome the problem of arithmetic with large integers. Finally, theresults of the implementation are given for $n=32, 64, 128$.''

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