Browsing by Subject "Logic programming languages"
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Item Automated reasoning about actions(2005) Lee, Joohyung; Lifschitz, VladimirItem Expressiveness of answer set languages(2007) Ferraris, Paolo, 1972-; Lifschitz, VladimirAnswer set programming (ASP) is a form of declarative programming oriented towards difficult combinatorial search problems. It has been applied, for instance, to plan generation and product configuration problems in artificial intelligence and to graph-theoretic problems arising in VLSI design and in historical linguistics. Syntactically, ASP programs look like Prolog programs, but the computational mechanisms used in ASP are different: they are based on the ideas that have led to the development of fast satisfiability solvers for propositional logic. ASP is based on the answer set/stable model semantics for logic problems, originally intended as a specification for query answering in Prolog. From the original definition of 1988, the semantics was independently extended by different research groups to more expressive kinds of programs, with syntax and semantics that are incompatible with each other. In this thesis we study how the various extensions are related to each other. In order to do that, we propose another definition of an answer set. This definition has three main characteristics: (i) it is very simple, (ii) its syntax is more general than the usual concept of a logic program, and (iii) strong theoretical tools can be used to reason on it. About (ii), we show that our syntax allows constructs defined in many other extensions of the answer sets semantics. This fact, together with (iii), allows us to study the expressiveness of those constructs. We also compare the answer set semantics with another important formalism developed by Norm McCain and Hudson Turner, called logic.Item Modeling hybrid domains using process description language(Texas Tech University, 2004-12) Chintabathina, SandeepResearchers in the field of knowledge representation and logic programming are constantly trying to come up with better ways to represent knowledge. One of the recent attempts is to model dynamic domains. A dynamic domain consists of actions that are capable of changing the properties of objects in the domain, for example the blocks world domain. Such domains can be modeled by action theories - collection of statements in so called action languages specifically designed for this purpose. In this thesis we extend this work to allow for continuous processes properties of objects that change continuously with time. For example the height of a freely falling object. In order to do this we adopt an action language/logic programming approach. A new action language called process description language is introduced that will be useful to model systems that exhibit both continuous and discrete behavior (also called hybrid systems). An example of a hybrid domain is the domain consisting of a freely falling object. A freely falling object is in the state of falling, which is a discrete property that can be changed only by actions (also called fluent) while its height is a continuous process. The syntax, semantics, and translation of the statements of the language into rules of a logic program will be discussed. Examples of domains that can represented in this language will be given. In addition, some planning and diagnostic problems will be discussed. Finally, the language will be compared with other languages used for similar purposes.