Graphs of the single-step operator for first-order logic programs-displayed in the real plane-exhibit self-similar structures known from topological dynamics, i.e., they appear to be fractals , or more precisely, attr...
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We address the problem of defining semantics for logic programs in presence of incomplete and contradictory information coming from different sources. The information consists of facts that a central server collects a...
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We address the problem of defining semantics for logic programs in presence of incomplete and contradictory information coming from different sources. The information consists of facts that a central server collects and tries to combine using (a) a set of logical rules, that is, a logic program, and (b) a hypothesis representing the server's own estimates. In such a setting incomplete information from a source or contradictory information from different sources necessitate the use of many-valued logics in which programs can be evaluated and hypotheses can be tested. To carry out such activities we propose a formal framework based on bilattices such as Belnap's four-valued logics. In this framework we work with the class of programs defined by Fitting and we propose hypothesis-based semantics for such programs. We also establish an intuitively appealing connection between our hypothesis testing mechanism, on the one hand, and the well-founded semantics and Kripke-Kleene semantics of Datalog programs with negation, on the other hand.
In this paper we propose a new way to represent P systems with active membranes based on logic programming techniques. This representation allows us to express the set of rules and the configuration of the P system in...
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In this paper we propose a new way to represent P systems with active membranes based on logic programming techniques. This representation allows us to express the set of rules and the configuration of the P system in each step of the evolution as literals of an appropriate language of first order logic. We provide a Prolog program to simulate the evolution of these P systems and present some auxiliary tools to simulate the evolution of a, P system with active membranes using 2-division which solves the SAT problem following the techniqnes presented in Reference.
The logic of bunched implications, BI, is a substructural system which freely combines an additive (intuitionistic) and a multiplicative (linear) implication via bunches (contexts with two combining operations, one wh...
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The logic of bunched implications, BI, is a substructural system which freely combines an additive (intuitionistic) and a multiplicative (linear) implication via bunches (contexts with two combining operations, one which admits Weakening and Contraction and one which does not). BI may be seen to arise from two main perspectives. On the one hand, from proof-theoretic or categorical concerns and, on the other, from a possible-worlds semantics based on preordered (commutative) monoids. This semantics may be motivated from a basic model of the notion of resource. We explain BI's proof-theoretic, categorical and semantic origins. We discuss in detail the question of completeness, explaining the essential distinction between BI with and without perpendicular to (the unit of boolean OR). We give an extensive discussion of BI as a semantically based logic of resources, giving concrete models based on Petri nets, ambients, computer memory, logic programming, and money. (C) 2003 Published by Elsevier B.V.
Starting from the early days of multi-agent systems research, considerable effort has been devoted to giving formal foundations to agent technologies. Work done in this direction, based on computational logic, is an a...
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Starting from the early days of multi-agent systems research, considerable effort has been devoted to giving formal foundations to agent technologies. Work done in this direction, based on computational logic, is an attempt to bridge an existing gap, between theoretical frameworks and their practical implementations. In the last two editions of the workshop on Computational logic in Multi-Agent Systems, CLIMA'01 and CLIMA'02, two discussion panels have been organized, aimed at bringing researchers together and exchanging ideas on a number of topics. In this article, we elaborate on the outcome of such panels, to draw some considerations about the recent advances and future directions of Computational logic in Multi-Agent Systems.
This paper presents a high-level hardware description environment developed at Queen's University, Belfast, U.K., which aims to bridge the gap between application design and hardware description. The environment, ...
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This paper presents a high-level hardware description environment developed at Queen's University, Belfast, U.K., which aims to bridge the gap between application design and hardware description. The environment, called application-to-hardware (A2H), allows for efficient compilation of high-level application descriptions to field programmable gate array (FPGA) hardware in the form of EDIF netlist in seconds. A key concept in bridging the gap while retaining the hardware efficiency, is that of hardware skeletons. A hardware skeleton is a parameterized description of a task-specific architecture, to which the user can supply not only value parameters but also functions or even other skeletons. A skeleton contains built-in rules, which capture optimizations specific to the target hardware at the implementation phase. The rule-based logic programming language Prolog has been chosen as the base notation for the A2H environment. This paper includes descriptions of hardware skeletons abstractions in the particular context of image processing applications. The current implementation of our system targets Xilinx XC4000 and Virtex series FPGAs.
In Classical Decision Theory, preferences and uncertainties of a decision maker (DM) have the quantitative forms of a utility function and a probability distribution. However, a numerical approach for decision making ...
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ISBN:
(纸本)3540229590
In Classical Decision Theory, preferences and uncertainties of a decision maker (DM) have the quantitative forms of a utility function and a probability distribution. However, a numerical approach for decision making suffers from a knowledge acquisition problem. In this paper a qualitative model for decision making is proposed, where the DM is modeled as the agent with preferences and beliefs about the world. Decision problem is represented by means of Brewka's logic program with ordered disjunction (LPOD) and a decision making process is a constraint satisfaction problem, where a solution is consistent with a knowledge base and maximally consistent with the DM's beliefs and preferences.
An odd cycle of a logic program is a simple cycle that has an odd number of negative edges in the dependency graph of the program. Similarly, an even cycle is one that has an even number of negative edges. For a norma...
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ISBN:
(纸本)0262511835
An odd cycle of a logic program is a simple cycle that has an odd number of negative edges in the dependency graph of the program. Similarly, an even cycle is one that has an even number of negative edges. For a normal logic program that has no odd cycles, while it is known that such a program always has a stable model, and such a stable model can be computed in polynomial time, we show in this paper that checking whether an atom is in a stable model is NP-complete, and checking whether an atom is in all stable models is co-NP complete, both are the same as in the general case for normal logic programs. Furthermore, we show that if a normal logic program has exactly one odd cycle, then checking whether it has a stable model is NP-complete, again the same as in the general case. For normal logic programs with a fixed number of even cycles, we show that there is a polynomial time algorithm for computing all stable models. Furthermore, this polynomial time algorithm can be improved significantly if the number of odd cycles is also fixed.
In this paper, we address the problem of checking whether two disjunctive logic programs possess exactly the same stable models. An existing translation-based method [14], which was designed for weight constraint prog...
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ISBN:
(纸本)354020721X
In this paper, we address the problem of checking whether two disjunctive logic programs possess exactly the same stable models. An existing translation-based method [14], which was designed for weight constraint programs supported by the SMODELS system, is generalized to the disjunctive case. Moreover, we report on our preliminary experiments with an implementation of the method, a translator called DLPEQ.
Inductive logic programming (ILP) is built on a foundation laid by research in machine learning and computational logic. Armed with this strong foundation, ILP has been applied to important and interesting problems in...
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Inductive logic programming (ILP) is built on a foundation laid by research in machine learning and computational logic. Armed with this strong foundation, ILP has been applied to important and interesting problems in the life sciences, engineering and the arts. This paper begins by briefly reviewing some example applications, in order to illustrate the benefits of ILP. In turn, the applications have brought into focus the need for more research into specific topics. We enumerate and elaborate five of these: (1) novel search methods;(2) incorporation of explicit probabilities;(3) incorporation of special-purpose reasoners;(4) parallel execution using commodity components;and (5) enhanced human interaction. It is our hypothesis that progress in each of these areas can greatly improve the contributions that can be made with ILP;and that, with assistance from research workers in other areas, significant progress in each of these areas is possible.
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