CAT: the copying approach to tabling

© Springer-Verlag Berlin Heidelberg 1998. The SLG-WAM implements tabling by freezing the WAM stacks: this technique has a reasonably small execution overhead, but is not easy to implement on top of an existing Prolog system. We propose a new technique for the implementation of tabling: the Copying Approach to Tabling. CAT does not interfere with normal Prolog execution and can be introduced in an existing Prolog system orthogonally. We have implemented CAT starting from XSB by taking out SLG-WAM and adding CAT. We describe the additions needed for adopting CAT in a WAM implementation. We show a case in which CAT performs arbitrarily worse than SLG-WAM, but on the other hand we present empirical evidence that CAT is competitive and often faster than SLG-WAM. We discuss issues related to memory management and the impact of the scheduling.status: publishe