Color confinement and the quantum-chromodynamic vacuum. II. Gluon propagation and the Coulomb int... more Color confinement and the quantum-chromodynamic vacuum. II. Gluon propagation and the Coulomb interaction. Jose Luis Rodriguez Marrero and Arthur R. Swift Department of Physics and Astronomy, University of Massachusetts, Amherst, Massachusetts 01003. ...
Abductive logic programming offers a formalism to declaratively express and solve problems in are... more Abductive logic programming offers a formalism to declaratively express and solve problems in areas such as diagnosis, planning, belief revision and hypothetical reasoning. Tabled logic programming offers a computational mechanism that provides a level of declarativity superior to that of Prolog, and which has supported successful applications in fields such as parsing, program analysis, and model checking. In this paper we show how to use tabled logic programming to evaluate queries to abductive frameworks with integrity constraints when these frameworks contain both default and explicit negation. The result is the ability to compute abduction over well-founded semantics with explicit negation and answer sets. Our approach consists of a transformation and an evaluation method. The transformation adjoins to each objective literal $O$ in a program, an objective literal $not(O)$ along with rules that ensure that $not(O)$ will be true if and only if $O$ is false. We call the resulting program a {\em dual} program. The evaluation method, \wfsmeth, then operates on the dual program. \wfsmeth{} is sound and complete for evaluating queries to abductive frameworks whose entailment method is based on either the well-founded semantics with explicit negation, or on answer sets. Further, \wfsmeth{} is asymptotically as efficient as any known method for either class of problems. In addition, when abduction is not desired, \wfsmeth{} operating on a dual program provides a novel tabling method for evaluating queries to ground extended programs whose complexity and termination properties are similar to those of the best tabling methods for the well-founded semantics. A publicly available meta-interpreter has been developed for \wfsmeth{} using the XSB system.
Para los ecólogos, una población es un conjunto de individuos de la misma especie que viven sufic... more Para los ecólogos, una población es un conjunto de individuos de la misma especie que viven suficientemente cerca unos de otros como para poder cruzarse. Algunas poblaciones tienen un número de individuos muy estable en el tiempo mientras en otras el numero de individuos aumenta, disminuye o fluctúa. Los ecólogos de poblaciones se ocupan de explicar y predecir estos diferentes comportamientos.
Color confinement and the quantum-chromodynamic vacuum. II. Gluon propagation and the Coulomb int... more Color confinement and the quantum-chromodynamic vacuum. II. Gluon propagation and the Coulomb interaction. Jose Luis Rodriguez Marrero and Arthur R. Swift Department of Physics and Astronomy, University of Massachusetts, Amherst, Massachusetts 01003. ...
Abductive logic programming offers a formalism to declaratively express and solve problems in are... more Abductive logic programming offers a formalism to declaratively express and solve problems in areas such as diagnosis, planning, belief revision and hypothetical reasoning. Tabled logic programming offers a computational mechanism that provides a level of declarativity superior to that of Prolog, and which has supported successful applications in fields such as parsing, program analysis, and model checking. In this paper we show how to use tabled logic programming to evaluate queries to abductive frameworks with integrity constraints when these frameworks contain both default and explicit negation. The result is the ability to compute abduction over well-founded semantics with explicit negation and answer sets. Our approach consists of a transformation and an evaluation method. The transformation adjoins to each objective literal $O$ in a program, an objective literal $not(O)$ along with rules that ensure that $not(O)$ will be true if and only if $O$ is false. We call the resulting program a {\em dual} program. The evaluation method, \wfsmeth, then operates on the dual program. \wfsmeth{} is sound and complete for evaluating queries to abductive frameworks whose entailment method is based on either the well-founded semantics with explicit negation, or on answer sets. Further, \wfsmeth{} is asymptotically as efficient as any known method for either class of problems. In addition, when abduction is not desired, \wfsmeth{} operating on a dual program provides a novel tabling method for evaluating queries to ground extended programs whose complexity and termination properties are similar to those of the best tabling methods for the well-founded semantics. A publicly available meta-interpreter has been developed for \wfsmeth{} using the XSB system.
Para los ecólogos, una población es un conjunto de individuos de la misma especie que viven sufic... more Para los ecólogos, una población es un conjunto de individuos de la misma especie que viven suficientemente cerca unos de otros como para poder cruzarse. Algunas poblaciones tienen un número de individuos muy estable en el tiempo mientras en otras el numero de individuos aumenta, disminuye o fluctúa. Los ecólogos de poblaciones se ocupan de explicar y predecir estos diferentes comportamientos.
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