Title
Complexity of fuzzy answer set programming under Łukasiewicz semantics.
Abstract
Fuzzy answer set programming (FASP) is a generalization of answer set programming (ASP) in which propositions are allowed to be graded. Little is known about the computational complexity of FASP and almost no techniques are available to compute the answer sets of a FASP program. In this paper, we analyze the computational complexity of FASP under Łukasiewicz semantics. In particular we show that the complexity of the main reasoning tasks is located at the first level of the polynomial hierarchy, even for disjunctive FASP programs for which reasoning is classically located at the second level. Moreover, we show a reduction from reasoning with such FASP programs to bilevel linear programming, thus opening the door to practical applications. For definite FASP programs we can show P-membership. Surprisingly, when allowing disjunctions to occur in the body of rules – a syntactic generalization which does not affect the expressivity of ASP in the classical case – the picture changes drastically. In particular, reasoning tasks are then located at the second level of the polynomial hierarchy, while for simple FASP programs, we can only show that the unique answer set can be found in pseudo-polynomial time. Moreover, the connection to an existing open problem about integer equations suggests that the problem of fully characterizing the complexity of FASP in this more general setting is not likely to have an easy solution.
Year
DOI
Venue
2014
10.1016/j.ijar.2013.10.011
International Journal of Approximate Reasoning
Keywords
Field
DocType
Answer set programming,Łukasiewicz logic,Computational complexity
Polynomial hierarchy,Łukasiewicz logic,Open problem,Computer science,Theoretical computer science,Linear programming,Artificial intelligence,Answer set programming,Discrete mathematics,Fuzzy logic,Machine learning,Semantics,Computational complexity theory
Journal
Volume
Issue
ISSN
55
9
0888-613X
Citations 
PageRank 
References 
8
0.52
30
Authors
4
Name
Order
Citations
PageRank
Marjon Blondeel1152.68
Steven Schockaert258357.95
Dirk Vermeir369485.34
Martine De Cock4134196.06