Efficient set operations over k2-trees

Abstract

k2-trees have been proved successful to represent in a very compact way differentkinds of binary relations, such as web graphs, RDFs or raster data. In order to be afully functional succinct representation for these domains, thek2-tree must support all therequired operations for binary relations. In their original description, the authors includehow to answer some of the most relevant queries over thek2-tree. In this paper, we extendthis functionality and detail the algorithms to efficiently compute thek2-tree resulting fromthe union, intersection, difference or complement of binary relations represented usingk2-trees.