TY - JOUR
T1 - Efficient top-down computation of queries under the well-founded semantics
AU - Chen, Weidong
AU - Swift, Terrance
AU - Warren, David S.
N1 - Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 1995/9
Y1 - 1995/9
N2 - The well-founded model provides a natural and robust semantics for logic programs with negative literals in rule bodies. Although various procedural semantics have been proposed for query evaluation under the well-founded semantics, the practical issues of implementation for effective and efficient computation of queries have been rarely discussed. This paper investigates two major implementation issues of query evaluation under the well-founded semantics, namely, (a) to ensure that negative literals be resolved only after their positive counterparts have been completely evaluated, and (b) to detect and handle potential negative loops. We present efficient incremental algorithms for maintaining positive and negative dependencies among subgoals in a top-down evaluation. Both completely evaluated subgoals and potential negative loops are detected by inspecting the dependency information of a single subgoal. Our implementation can be viewed as an effective successor to SLDNF resolution, extending Prolog computation in a natural and smooth way.
AB - The well-founded model provides a natural and robust semantics for logic programs with negative literals in rule bodies. Although various procedural semantics have been proposed for query evaluation under the well-founded semantics, the practical issues of implementation for effective and efficient computation of queries have been rarely discussed. This paper investigates two major implementation issues of query evaluation under the well-founded semantics, namely, (a) to ensure that negative literals be resolved only after their positive counterparts have been completely evaluated, and (b) to detect and handle potential negative loops. We present efficient incremental algorithms for maintaining positive and negative dependencies among subgoals in a top-down evaluation. Both completely evaluated subgoals and potential negative loops are detected by inspecting the dependency information of a single subgoal. Our implementation can be viewed as an effective successor to SLDNF resolution, extending Prolog computation in a natural and smooth way.
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U2 - 10.1016/0743-1066(94)00028-5
DO - 10.1016/0743-1066(94)00028-5
M3 - Article
AN - SCOPUS:0001425243
VL - 24
SP - 161
EP - 199
JO - The Journal of Logic Programming
JF - The Journal of Logic Programming
SN - 0743-1066
IS - 3
ER -