LAZY STRUCTURE SHARING FOR QUERY OPTIMIZATION

We study lazy structure sharing as a tool for optimizing equivalence t esting on complex data types, We investigate a number of strategies fo r implementing lazy structure sharing and provide upper and lower boun ds on their performance (how quickly they effect ideal configurations of our data structure). In most cases when the strategies are applied to a restricted case of the problem, the bounds provide nontrivial imp rovements over the naive linear-time equivalence-testing strategy that employs no optimization. Only one strategy, however, which employs pa th compression, seems promising for the most general case of the probl em.