Gerald Pfeifer

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Disjunctive Logic Programming (DLP) is an advanced formalism for knowledge representation and reasoning, which is very expressive in a precise mathematical sense: it allows one to express <i>every</i> property of finite structures that is decidable in the complexity class &#931;<sup><i>P</i></sup><sub>2</sub> (NP<sup>NP</sup>). Thus, under widely believed(More)
The addition of aggregates has been one of the most relevant enhancements to the language of answer set programming (ASP). They strengthen the modeling power of ASP, in terms of concise problem representations. While many important problems can be encoded using nonrecursive aggregates, some relevant examples lend themselves for the use of recursive(More)
The addition of aggregates has been one of the most relevant enhancements to the language of answer set programming (ASP). They strengthen the modelling power of ASP in terms of natural and concise problem representations. Previous semantic definitions typically agree in the case of nonrecursive aggregates, but the picture is less clear for aggregates(More)
dlv is a knowledge representation system, based on disjunctive logic programming, which ooers front-ends to several advanced KR formalisms. The system has been developed since one year at the Technical University of Vienna in an ongoing project funded by the Austrian Science Funds. After a report on the current state of the art in the implementation of dlv(More)
We propose a new declarative planning language, called K, which is based on principles and methods of logic programming. In this language, transitions between states of knowledge can be described, rather than transitions between completely described states of the world, which makes the language well-suited for planning under incomplete knowledge.(More)
Disjunctive Deductive Databases (DDDBs) | function-free disjunctive logic programs with negation in rule bodies allowed | have been recently recognized as a powerful tool for knowledge representation and commonsense reasoning. Much research has been spent on issues like semantics and complexity of DDDBs, but the important area of implementing DDDBs has been(More)
Disjunctive Logic Programming (DLP) is a very expressive formalism: it allows to express every property of finite structures that is decidable in the complexity class E^ (NP H ) . Despite the high expressiveness of DLP, there are some simple properties, often arising in real-world applications, which cannot be encoded in a simple and natural manner. Among(More)
Disjunctive Logic Programming (DLP) is a very expressive formalism: it allows for expressing every property of finite structures that is decidable in the complexity class Σ2(=NP ). Despite this high expressiveness, there are some simple properties, often arising in real-world applications, which cannot be encoded in a simple and natural manner. Especially(More)
The need for representing indeenite information led to disjunctive de-ductive databases, which also fertilized work on disjunctive logic programming. Based on this paradigm, the DLV system has been designed and implemented as a tool for declarative knowledge representation. In this paper, we focus on the usage of DLV for solving problems in a declarative(More)
We propose a new declarative planning language, called K, which is based on principles and methods of logic programming. In this language, transitions between states of knowledge can be described, rather than transitions between completely described states of the world, which makes the language well suited for planning under incomplete knowledge.(More)