منابع مشابه
On basic forbidden patterns of functions
The allowed patterns of a map on a one-dimensional interval are those permutations that are realized by the relative order of the elements in its orbits. The set of allowed patterns is completely determined by the minimal patterns that are not allowed. These are called basic forbidden patterns. In this paper we study basic forbidden patterns of several functions. We show that the logistic map L...
متن کاملstudy of hash functions based on chaotic maps
توابع درهم نقش بسیار مهم در سیستم های رمزنگاری و پروتکل های امنیتی دارند. در سیستم های رمزنگاری برای دستیابی به احراز درستی و اصالت داده دو روش مورد استفاده قرار می گیرند که عبارتند از توابع رمزنگاری کلیددار و توابع درهم ساز. توابع درهم ساز، توابعی هستند که هر متن با طول دلخواه را به دنباله ای با طول ثابت تبدیل می کنند. از جمله پرکاربردترین و معروف ترین توابع درهم می توان توابع درهم ساز md4, md...
Forbidden Patterns
We consider the problem of indexing a collection of documents (a.k.a. strings) of total length n such that the following kind of queries are supported: given two patterns P and P−, list all nmatch documents containing P but not P−. This is a natural extension of the classic problem of document listing as considered by Muthukrishnan [SODA’02], where only the positive pattern P is given. Our main...
متن کاملLinear bound on extremal functions of some forbidden patterns in 0-1 matrices
In this paper by saying that a 0-1 matrix A avoids a pattern P given as a 0-1 matrix we mean that no submatrix of A either equals P or can be transformed into P by replacing some 1 entries with 0 entries. We present a new method for estimating the maximal number of the 1 entries in a matrix that avoids certain pattern. Applying this method we give a linear bound on the maximal number ex(n, L1) ...
متن کاملOrdering without Forbidden Patterns
Let F be a set of ordered patterns, i.e., graphs whose vertices are linearly ordered. An F-free ordering of the vertices of a graph H is a linear ordering of V (H) such that none of the patterns in F occurs as an induced ordered subgraph. We denote by Ord(F) the decision problem asking whether an input graph admits an F-free ordering; we also use Ord(F) to denote the class of graphs that do adm...
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ژورنال
عنوان ژورنال: Discrete Applied Mathematics
سال: 2011
ISSN: 0166-218X
DOI: 10.1016/j.dam.2011.04.012