A Technique for Extending Rapid Exact-Match String Matching to Arrays of More than One Dimension

Abstract

A class of algorithms is presented for very rapid on-line detection of occurrences of a fixed set of pattern arrays as embedded subarrays in an input array. By reducing the array problem to a string matching problem in a natural way, it is shown that efficient string matching algorithms may be applied to arrays. This is illustrated by use of the string-matching algorithm of Knuth, Morris and Pratt [7]. Depending on the data structure used for the preprocessed pattern graph, this algorithm may be made to run “real-time” or merely in linear time. Extensions can be made to nonrectangular arrays, multiple arrays of dissimilar sizes, and arrays of more than two dimensions. Possible applications are foreseen to problems such as detection of edges in digital pictures and detection of local conditions in board games.