Systolic algorithms for tree pattern matching

The objective of tree matching is to find the set of nodes at which a pattern tree matches a subject tree. Several sequential and parallel algorithms have been proposed in the literature for this compute bound problem. Most of the parallel algorithms are based on the theoretical PRAM model of computation. In this paper, we propose two efficient parallel algorithms for tree pattern matching based on the linear systolic array model. The algorithms can be mapped onto any SIMD machine. The algorithms require O(n+m) time to perform the matching using either n or m processors, where n is the size of the subject tree and m is the size of the pattern tree. The algorithms represent a significant improvement over the existing ones in view of implementation