Hierarchy encoding with multiple genes

Abstract

Efficient implementation of type inclusion testing is important for data and knowledge base systems employing large hierarchies. The bit vector encoding of a partially ordered set representing a type hierarchy permits constant-time type inclusion testing. Current such methods employ a simple encoding, associating a single gene for each join-irreducible element. We present an algorithm using multiple genes for those elements with many siblings. The new algorithm provides a significant improvement on the encoding size for hierarchies with low multiple inheritance factors. © 2008 Springer-Verlag Berlin Heidelberg.