Efficient Goal Directed Bottom-up Evaluation of Logic Programs

Keyword(s):  
Author(s):  
Céline Hocquette ◽  
Stephen H. Muggleton

Predicate Invention in Meta-Interpretive Learning (MIL) is generally based on a top-down approach, and the search for a consistent hypothesis is carried out starting from the positive examples as goals. We consider augmenting top-down MIL systems with a bottom-up step during which the background knowledge is generalised with an extension of the immediate consequence operator for second-order logic programs. This new method provides a way to perform extensive predicate invention useful for feature discovery. We demonstrate this method is complete with respect to a fragment of dyadic datalog. We theoretically prove this method reduces the number of clauses to be learned for the top-down learner, which in turn can reduce the sample complexity. We formalise an equivalence relation for predicates which is used to eliminate redundant predicates. Our experimental results suggest pairing the state-of-the-art MIL system Metagol with an initial bottom-up step can significantly improve learning performance.


1994 ◽  
Vol 124 (1) ◽  
pp. 93-125 ◽  
Author(s):  
Michael Codish ◽  
Dennis Dams ◽  
Eyal Yardeni

1991 ◽  
Vol 7 (3) ◽  
pp. 337-358 ◽  
Author(s):  
Danny De Schreye ◽  
Bern Martens ◽  
Gunther Sablon ◽  
Maurice Bruynooghe
Keyword(s):  
Top Down ◽  

2014 ◽  
Vol 15 (6) ◽  
pp. 854-889 ◽  
Author(s):  
MARCO CALAUTTI ◽  
SERGIO GRECO ◽  
FRANCESCA SPEZZANO ◽  
IRINA TRUBITSYNA

AbstractRecently, there has been an increasing interest in the bottom-up evaluation of the semantics of logic programs with complex terms. The presence of function symbols in the program may render the ground instantiation infinite, and finiteness of models and termination of the evaluation procedure, in the general case, are not guaranteed anymore. Since the program termination problem is undecidable in the general case, several decidable criteria (called program termination criteria) have been recently proposed. However, current conditions are not able to identify even simple programs, whose bottom-up execution always terminates. The paper introduces new decidable criteria for checking termination of logic programs with function symbols under bottom-up evaluation, by deeply analyzing the program structure. First, we analyze the propagation of complex terms among arguments by means of the extended version of the argument graph calledpropagation graph. The resulting criterion, calledacyclicity, generalizes most of the decidable criteria proposed so far. Next, we study how rules may activate each other and define a more powerful criterion, calledsafety. This criterion uses the so-calledsafety functionable to analyze how rules may activate each other and how the presence of some arguments in a rule limits its activation. We also study the application of the proposed criteria to bound queries and show that the safety criterion is well-suited to identify relevant classes of programs and bound queries. Finally, we propose a hierarchy of classes of terminating programs, calledk-safety, where thek-safe class strictly includes the (k-1)-safe class.


1993 ◽  
Vol 47 (3) ◽  
pp. 149-157
Author(s):  
Byeong-Mo Chang ◽  
Kwang-Moo Choe ◽  
Taisook Han

Author(s):  
Raghu Ramakrishnan ◽  
Divesh Srivastava ◽  
S. Sudarshan
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