We consider the problem of pattern matching with k mismatches, where there can be don't care or wild card characters in the pattern. Specifically, given a pattern P of length m and a text T of length n, we want to find all occurrences of P in T that have no more than k mismatches. The pattern can have don't care characters, which match any character. Without don't cares, the best known algorith...

Text based pictures called text art or ASCII art are often used in Web pages, email text and so on. They enrich expression in text data, but they can be noise for text processing and display of text. For example, they can be obstacle for text-to-speech software and natural language processing, and some of them lose their shape in small display devices. With Text art extraction methods, which de...

The Apostolico-Giancarlo string-matching algorithm is analyzed precisely. We give a tight upper bound of 3 2 n text characters comparisons when searching for a pattern in a text of length n. We exhibit a family of patterns and texts reaching this bound. We also provide a slightly improved version of the algorithm.

Automatic Text location, character recognition and image understanding of a given paper document are main objectives of computer vision area. The rst stage for these problems is extracting text information and separating graphic symbol from texts. Previous text location algorithm could not extract the negative text(e.g., newspaper headline) which is a white colored text on some solid background...

In this paper we have presented new algorithms to handle the pattern matching problem where the pattern can contain variable length gaps. Given a pattern P with variable length gaps and a text T our algorithm works in O(n + m + α log(max1<=i<=l(bi − ai))) time where n is the length of the text, m is the summation of the lengths of the component subpatterns, α is the total number of occurrences ...

We formally define a class of sequential pattern matching algorithms that includes all variations of Morris-Pratt algorithm. For last twenty years it was known that complexity of such algorithms are bounded by a linear function of the text string length. Recenlly, substantial progress has been made in identifying lower bounds. However, it was not known whether really there exists asymptotically...

We present an efficient algorithm for computing the LZ78 factorization of a text, where the text is represented as a straight line program (SLP), which is a context free grammar in the Chomsky normal form that generates a single string. Given an SLP of size n representing a text S of length N , our algorithm computes the LZ78 factorization of T in O(n √ N + m logN) time and O(n √ N + m) space, ...

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In this article we apply a method for encrypting messages based on the properties of the quasigroups According to the analysis given in the article the method is extremely secure Beside that the plain text and its cipher text are of the same length and the encoding is of stream nature guarantying a very fast implementation AMS Mathematics Subject Classi cation A P N