In this paper, we present a syntactic transformation, called the unfolding operator, that allows forgetting an atom in a logic program (under ASP semantics). the main advantage of unfolding is that, unlike other synta...
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ISBN:
(纸本)9783031157073;9783031157066
In this paper, we present a syntactic transformation, called the unfolding operator, that allows forgetting an atom in a logic program (under ASP semantics). the main advantage of unfolding is that, unlike other syntactic operators, it is always applicable and guarantees strong persistence, that is, the result preserves the same stable models with respect to any context where the forgotten atom does not occur. the price for its completeness is that the result is an expression that may contain the fork operator. Yet, we illustrate how, in some cases, the application of fork properties may allow us to reduce the fork to a logic program, even in conditions that could not be treated before using the syntactic methods in the literature.
A Abstract argumentation and Dung's framework are popular for modeling and evaluating arguments in artificial intelligence. We consider various counting problems in abstract argumentation under practical aspects. ...
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ISBN:
(纸本)9783031157073;9783031157066
A Abstract argumentation and Dung's framework are popular for modeling and evaluating arguments in artificial intelligence. We consider various counting problems in abstract argumentation under practical aspects. We revisit algorithms and establish a framework that employs dynamic programming on tree decompositions for counting extensions of abstract argumentation frameworks under admissible, stable, and complete semantics. We provide an empirical evaluation and investigate conditions under which our approach is useful.
Modal logic S5 is used extensively for representing knowledge that includes statements about necessity and possibility, owing to its simplicity in handling chained modal operators. Significant research effort has been...
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ISBN:
(纸本)9783031157073;9783031157066
Modal logic S5 is used extensively for representing knowledge that includes statements about necessity and possibility, owing to its simplicity in handling chained modal operators. Significant research effort has been devoted in developing efficient reasoning mechanisms over complex S5 formulas, resulting in various solvers taking advantage of the boolean satisfiability problem (SAT). Among them, the most performant solver implements a heuristic for identifying worlds that can be merged, hence reducing the size of SAT instances to be checked. Recently, Answer Set programming (ASP) has also been considered, and different ASP encodings were proposed and tested, reaching state-of-the-art performance. In particular, a heuristic for identifying the propositional atoms that are relevant in every world resulted in a performance gain in previous experiments. this work addresses the open question of whether the aforementioned two heuristics can be combined, as well as possibly enabling lazy instantiation of the resulting encodings, and what their potential impact is on the performance of the ASP-based solver. Experiments show that lazy creation of worlds provides some further performance gain to the ASP-based solver on the tested instances.
In this paper, we present a system, called xASP, for generating explanations that explain why an atom belongs to (or does not belong to) an answer set of a given program. the system can generate all possible explanati...
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ISBN:
(纸本)9783031157073;9783031157066
In this paper, we present a system, called xASP, for generating explanations that explain why an atom belongs to (or does not belong to) an answer set of a given program. the system can generate all possible explanations for a query without the need to simplify the program before computing explanations, i.e., it works with non-ground programs. these properties distinguish xASP from existing systems such as xClingo, DiscASP, exp(ASP(c)), and s(CASP), which also generate explanations for queries to logic programs under the answer set semantics but simplify and ground the programs (the three systems xClingo, DiscASP, exp(ASP(c))) or do not always generate all possible explanations (the system s(CASP)). In addition, the output of xASP is insensitive to syntactic variations such as the order conditions and the order of rules, which is also different from the output of s(CASP).
Several AI problems can be conveniently modelled in ASP, and many of them require to enumerate solutions characterized by an optimality property that can be expressed in terms of subset-minimality with respect to some...
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ISBN:
(纸本)9783031157073;9783031157066
Several AI problems can be conveniently modelled in ASP, and many of them require to enumerate solutions characterized by an optimality property that can be expressed in terms of subset-minimality with respect to some objective atoms. In this context, solutions are often either (i) answer sets or (ii) sets of atoms that enforce the absence of answer sets on the ASP program at hand such sets are referred to as minimal unsatisfiable subsets (MUSes). In both cases, the required enumeration task is currently not supported by state-of-the-art ASP solvers.
In temporal extensions of Answer Set programming (ASP) based on linear-time, the behavior of dynamic systems is captured by sequences of states. While this representation reflects their relative order, it abstracts aw...
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ISBN:
(纸本)9783031157073;9783031157066
In temporal extensions of Answer Set programming (ASP) based on linear-time, the behavior of dynamic systems is captured by sequences of states. While this representation reflects their relative order, it abstracts away the specific times associated with each state. In many applications, however, timing constraints are important like, for instance, when planning and scheduling go hand in hand. We address this by developing a metric extension of linear-time temporal equilibrium logic, in which temporal operators are constrained by intervals over natural numbers. the resulting Metric Equilibrium logic provides the foundation of an ASP-based approach for specifying qualitative and quantitative dynamic constraints. To this end, we define a translation of metric formulas into monadic first-order formulas and give a correspondence between their models in Metric Equilibrium logic and Monadic Quantified Equilibrium logic, respectively. Interestingly, our translation provides a blue print for implementation in terms of ASP modulo difference constraints.
Using answer set programming in real-world applications requires that the answer set program is correct and adequately represents knowledge. In this paper, we present strategies to resolve unintended contradictory sta...
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ISBN:
(纸本)9783031157073;9783031157066
Using answer set programming in real-world applications requires that the answer set program is correct and adequately represents knowledge. In this paper, we present strategies to resolve unintended contradictory statements resulting from modelling gaps and other flaws by modifying the program without manipulating the actual conflicting rules (inconsistency-causing rules with complementary head literals). We show how latent conflicts can be detected to prevent further conflicts during the resolution process or after subsequent modifications in the future. the presented approach is another step towards a general framework where professional experts who are not necessarily familiar with ASP can repair existing answer set programs and independently resolve conflicts resulting from contradictory statements in an informative way. In such a framework, conflict resolution strategies allow for generating possible solutions that consist of informative extensions and modifications of the program. In interaction withthe professional expert, these solution options can then be used to obtain the solution that represents the underlying knowledge best.
Answer Set programming with Quantifiers ASP(Q) is a recent extension of Answer Set programming (ASP) that allows one to model problems from the entire polynomial hierarchy. Earlier work focused on demonstrating modeli...
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ISBN:
(纸本)9783031157073;9783031157066
Answer Set programming with Quantifiers ASP(Q) is a recent extension of Answer Set programming (ASP) that allows one to model problems from the entire polynomial hierarchy. Earlier work focused on demonstrating modeling capabilities of ASP(Q). In this paper, we propose a modular ASP(Q) solver that translates a quantified ASP program together with a given data instance into a Quantified Boolean Formula (QBF) to be solved by any QBF solver. We evaluate the performance of our solver on several instances and with different back-end QBF solvers, demonstrating the efficacy of ASP(Q) as a tool for rapid modeling and solving of complex combinatorial problems. the benchmark problems we use include two new ones, Argumentation Coherence and Para-coherent ASP, for which we develop elegant ASP(Q) encodings.
Answer Set programming (ASP) is a well-established declarative AI formalism for knowledge representation and reasoning. ASP systems were successfully applied to both industrial and academic problems. Nonetheless, thei...
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ISBN:
(纸本)9783031157073;9783031157066
Answer Set programming (ASP) is a well-established declarative AI formalism for knowledge representation and reasoning. ASP systems were successfully applied to both industrial and academic problems. Nonetheless, their performance can be improved by embedding domain-specific heuristics into their solving process. However, the development of domain-specific heuristics often requires both a deep knowledge of the domain at hand and a good understanding of the fundamental working principles of the ASP solvers. In this paper, we investigate the use of deep learning techniques to automatically generate domain-specific heuristics for ASP solvers targeting the well-known graph coloring problem. Empirical results show that the idea is promising: the performance of the ASP solver WASP can be improved.
Model-based safety assessment brings dependability modeling closer to the system design and allow for automated analysis of high-level models. RiskSpectrum ModelBuilder uses an object-oriented modeling language with e...
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