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26
Efficient 2dimensional Approximate Matching of Halfrectangular Figures
, 1993
"... Efficient algorithms exist for the approximate two dimensional matching problem for rectangles. This is the problem of finding all occurrences of an m \Theta m pattern in an n \Theta n text with no more than k mismatch, insertion, and deletion errors. In computer vision it is important to general ..."
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Cited by 31 (11 self)
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Efficient algorithms exist for the approximate two dimensional matching problem for rectangles. This is the problem of finding all occurrences of an m \Theta m pattern in an n \Theta n text with no more than k mismatch, insertion, and deletion errors. In computer vision it is important to generalize this problem to nonrectangular figures. We make progress towards this goal by defining halfrectangular figures of height m and area a. The approximate two dimensional matching problem for halfrectangular patterns can be solved using a dynamic programming approach in time O(an 2 ). We show an O(kn 2 p m log m p k log k + k 2 n 2 ) algorithm which combines convolutions with dynamic programming. Note that our algorithm is superior to previous known solutions for k m 1=3 . At the heart of the algorithm are the Smaller Matching Problem and the kAligned Ones with Location Problem. These are interesting problems in their own right. Efficient algorithms to solve both t...
Polytypic Pattern Matching
 In Conference Record of FPCA '95, SIGPLANSIGARCHWG2.8 Conference on Functional Programming Languages and Computer Architecture
, 1995
"... The (exact) pattern matching problem can be informally specified as follows: given a pattern and a text, find all occurrences of the pattern in the text. The pattern and the text may both be lists, or they may both be trees, or they may both be multidimensional arrays, etc. This paper describes a g ..."
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Cited by 28 (8 self)
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The (exact) pattern matching problem can be informally specified as follows: given a pattern and a text, find all occurrences of the pattern in the text. The pattern and the text may both be lists, or they may both be trees, or they may both be multidimensional arrays, etc. This paper describes a general patternmatching algorithm for all datatypes definable as an initial object in a category of F algebras, where F is a regular functor. This class of datatypes includes mutual recursive datatypes and lots of different kinds of trees. The algorithm is a generalisation of the Knuth, Morris, Pratt like patternmatching algorithm on trees first described by Hoffmann and O'Donnell. 1 Introduction Most editors provide a search function that takes a string of symbols and returns the first position in the text being edited at which this string of symbols occurs. The string of symbols is called a pattern, and the algorithm that detects the position at which a pattern occurs is called a (exa...
An Alphabet Independent Approach to Two Dimensional Matching
, 1994
"... There are many solutions to the string matching problem which are strictly linear in the input size and independent of alphabet size. Furthermore, the model of computation for these algorithms is very weak: they allow only simple arithmetic and comparisons of equality between characters of the in ..."
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Cited by 24 (8 self)
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There are many solutions to the string matching problem which are strictly linear in the input size and independent of alphabet size. Furthermore, the model of computation for these algorithms is very weak: they allow only simple arithmetic and comparisons of equality between characters of the input. In contrast, algorithm for two dimensional matching have needed stronger models of computation, most notably assuming a totally ordered alphabet. The fastest algorithms for two dimensional matching have therefore had a logarithmic dependence on the alphabet size. In the worst case, this gives an algorithm that runs in O(n log m) with O(m log m) preprocessing.
Approximate Pattern Matching with Samples
 In Proc. of ISAAC'94
, 1994
"... . We simplify in this paper the algorithm by Chang and Lawler for the approximate string matching problem, by adopting the concept of sampling. We have a more general analysis of expected time with the simplified algorithm for the onedimensional case under a nonuniform probability distribution ..."
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Cited by 22 (1 self)
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. We simplify in this paper the algorithm by Chang and Lawler for the approximate string matching problem, by adopting the concept of sampling. We have a more general analysis of expected time with the simplified algorithm for the onedimensional case under a nonuniform probability distribution, and we show that our method can easily be generalized to the twodimensional approximate pattern matching problem with sublinear expected time. 1 Introduction Since the inaugural papers on string matching algorithms were published by Knuth, Morris and Pratt[11] and Boyer and Moore [5], the problem diversified into various directions. Let us call string matching onedimensional pattern matching. One is twodimensional pattern matching and the other is approximate pattern matching where up to k differences are allowed for a match. Yet another theme is twodimensional approximate pattern matching. There are numerous papers in these new research areas. We cite just a few of them to compare...
Optimally Fast Parallel Algorithms for Preprocessing and Pattern Matching in One and Two Dimensions
, 1993
"... All algorithms below are optimal alphabetindependent parallel CRCW PRAM algorithms. In one dimension: Given a pattern string of length m for the stringmatching problem, we design an algorithm that computes a deterministic sample of a sufficiently long substring in constant time. This problem use ..."
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Cited by 19 (10 self)
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All algorithms below are optimal alphabetindependent parallel CRCW PRAM algorithms. In one dimension: Given a pattern string of length m for the stringmatching problem, we design an algorithm that computes a deterministic sample of a sufficiently long substring in constant time. This problem used to be a bottleneck in the pattern preprocessing for one and twodimensional pattern matching. The best previous time bound was O(log 2 m= log log m). We use this algorithm to obtain the following results. 1. Improving the preprocessing of the constanttime text search algorithm [12] from O(log 2 m= log log m) to O(log log m), which is now best possible. 2. A constanttime deterministic stringmatching algorithm in the case that the text length n satisfies n = \Omega\Gamma m 1+ffl ) for a constant ffl ? 0. 3. A simple probabilistic stringmatching algorithm that has constant time with high probability for random input. 4. A constant expected time LasVegas algorithm for computing t...
Efficient 2dimensional approximate matching of nonrectangular figures
 Proc. of 2nd Symoposium on Descrete Algorithms
, 1991
"... Finding all occurrences of a nonrectangular pattern of height m and area a in an nn text with no more than k mismatch, insertion, and deletion errors is an important problem in computer vision. It can be solved using a dynamic programming approach in time O(an 2). We show a O(kn 2 # m log m # k log ..."
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Cited by 18 (7 self)
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Finding all occurrences of a nonrectangular pattern of height m and area a in an nn text with no more than k mismatch, insertion, and deletion errors is an important problem in computer vision. It can be solved using a dynamic programming approach in time O(an 2). We show a O(kn 2 # m log m # k log k + k 2 n 2) algorithm which combines convolutions with dynamic programming. At the heart of the algorithm are the Smaller Matching Problem and the kAligned Ones with Location Problem. Efficient algorithms to solve both these problems are presented.
MultiMethod Dispatching: A Geometric Approach with Applications to String Matching Problems
, 1999
"... Current object oriented programming languages (OOPLs) rely on monomethod dispatching. Recent research has identified multimethods as a new, powerful feature to be added to OOPLs, and several experimental OOPLs now have multimethods. Their ultimate success and impact in practice depends, among ..."
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Cited by 15 (3 self)
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Current object oriented programming languages (OOPLs) rely on monomethod dispatching. Recent research has identified multimethods as a new, powerful feature to be added to OOPLs, and several experimental OOPLs now have multimethods. Their ultimate success and impact in practice depends, among other things, on whether multimethod dispatching can be supported efficiently. We show that the multimethod dispatching problem can be transformed to a geometric problem on multidimensional integer grids, for which we then develop a data structure that uses nearlinear space and has O(log log n) query time. This gives a solution whose performance almost matches that of the best known algorithm for standard monomethod dispatching. Our geometric data structure has other applications as well, namely in two string matching problems: matching multiple rectangular patterns against a rectangular query text, and approximate dictionary matching with edit distance at most one. Our results f...
Approximate Subset Matching with Don't Cares
"... The Subset Matching problem was recently introduced by Cole and Hariharan. The input of the problem is a text array of n sets totaling s elements and a pattern array of m sets totaling s0 elements. There is a match of the pattern in a text location if every pattern set is a subset of the correspondi ..."
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Cited by 13 (1 self)
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The Subset Matching problem was recently introduced by Cole and Hariharan. The input of the problem is a text array of n sets totaling s elements and a pattern array of m sets totaling s0 elements. There is a match of the pattern in a text location if every pattern set is a subset of the corresponding text set. Subset matching has proven to be a powerful technique and enabled finding an efficient solution to the Tree Matching problem. The subset matching model may prove useful in solving other hard problems, e.g. Swap Matching. In this paper we investigate the complexity of approximate subset matching with "don't care"s. We provide two algorithms for the problem. A randomized algorithm whose complexity is O((s + n + n m s 0)pm log2 m) and a deterministic algorithm whose complexity is O((s + n)ps0 log m).
Two Dimensional Dictionary Matching
 Information Processing Letters
, 1992
"... Most traditional pattern matching algorithms solve the problem of finding all occurrences of a given pattern string P in a given text T . Another important paradigm is the dictionary matching problem. Let D = {P 1 , ..., P k } be the dictionary. We seek all locations of dictionary patterns that a ..."
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Cited by 12 (3 self)
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Most traditional pattern matching algorithms solve the problem of finding all occurrences of a given pattern string P in a given text T . Another important paradigm is the dictionary matching problem. Let D = {P 1 , ..., P k } be the dictionary. We seek all locations of dictionary patterns that appear in a given text T .