A Linear Tabling Mechanism

14 years 3 months ago

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Delaying-based tabling mechanisms, such as the one adopted in XSB, are nonlinear in the sense that the computation state of delayed calls has to be preserved. In this paper, we present the implementation of a linear tabling mechanism. The key idea is to let a call execute from the backtracking point of a former variant call if such a call exists. The linear tabling mechanism has the following advantages over non-linear ones: (1) it is relatively easy to implement; (2) it imposes no overhead on standard Prolog programs; and (3) the cut operator works for a certain class of useful tabled programs and thus it is possible to use the cut operator to express negationas-failure and conditionals in those programs. The weakness of the linear mechanism is the necessity of re-computation for computing ﬁxpoints. However, we have found that re-computation can be avoided for a certain portion of calls of directly-recursive tabled predicates. We have implemented the linear tabling mechanism in B-P...

Neng-Fa Zhou, Yi-Dong Shen, Li-Yan Yuan, Jia-Huai

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