When modelling expert knowledge, default negation is very useful, but might lead to there being no stable models. Detecting the exact causes of the incoherence in the logic program manually can become quite cumbersome...
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Search-optimization problems are plentiful in scientific and engineering domains. MaxSAT and answer set programming with weak constraints (ASP-WC) are popular frameworks for modeling and solving search problems with o...
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Processing programs as data is one of the successes of functional and logic programming. Higher-order functions, as program-processing programs are called in functional programming, and meta-programs, as they are call...
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Processing programs as data is one of the successes of functional and logic programming. Higher-order functions, as program-processing programs are called in functional programming, and meta-programs, as they are called in logic programming, are widespread declarative programming techniques. In logic programming, there is a gap between the meta-programming practice and its theory: The formalizations of meta-programming do not explicitly address its impredicativity and are not fully adequate. This article aims at overcoming this unsatisfactory situation by discussing the relevance of impredicativity to meta-programming, by revisiting former formalizations of meta-programming, and by defining Reflective Predicate logic, a conservative extension of first-order logic, which provides a simple formalization of meta-programming.
Smart environments powered by the Internet of Things aim at improving our daily lives by automatically tuning ambient parameters (e.g. temperature, interior light) and by achieving energy savings through self-managing...
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Tile-based maps are used in a wide variety of games, including Zelda: Link’s Awakening, Super Mario Bros, and many tabletop role-playing games. They represent a relatively simple method for designing game worlds, whi...
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This paper presents the formalization for a system that monitors and enforces regulative time-constrained conditional norms through sanctioning, for agent societies. The representation here has the advantage of allowi...
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This paper presents the formalization for a system that monitors and enforces regulative time-constrained conditional norms through sanctioning, for agent societies. The representation here has the advantage of allowing for qualitative and quantitative interval-based temporal constraints between a norm's condition and its effect. The system possesses mechanisms for monitoring both norm compliance and violation of reified norms. Each norm has an identity, which enables the identification of norms violated or complied with. The formalism seamlessly treats violation- or conformance-handling norms (such as violation notification, sanctioning and rewarding norms) as regular norms. The implementation formalizes norms as logic program clauses, the head of which specifies what normative position (i.e. the norm's effect) an agent must observe within some time constraint of some arising situation;and the body of which describes a situation defined as the norm's pre-condition and the role that the implicated agent plays within it. For the purpose of imposing sanctions, the only violations deemed liable are those violations that the agent fails to mitigate by compliance with all relevant contrary-to-duty norms. An agent may ultimately be sanctioned for a liable norm while norm compliance is rewarded in the system. Sanctioning itself takes place in two norm-guided phases: the obligation of an enforcer agent to notify an erring agent of reparative actions it is obliged to take and the time constraint within which it should be taken, and a norm for monitoring the agent's compliance with the notification. The violation of the latter norm leads to the meting out of sanctions.
We present a concise source-to-source transformation that introduces justifications for user-defined constraints into the rule-based Constraint Handling Rules (CHR) programming language. There is no need to introduce ...
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We present a concise source-to-source transformation that introduces justifications for user-defined constraints into the rule-based Constraint Handling Rules (CHR) programming language. There is no need to introduce a new semantics for justifications. This leads to a conservative extension of the language, as we can show the equivalence of rule applications. A scheme of two rules suffices to allow for logical retraction (deletion, removal) of CHR constraints during computation. Without the need to recompute from scratch, these rules remove the constraint and also undo all its consequences. We prove a confluence result concerning the rule scheme. We prove its correctness in general and tighten the results for confluent programs. We give an implementation, show its correctness, present two classical examples of dynamic algorithms, and improve the implementation. The computational overhead of introducing justifications and of performing logical retraction, i.e. the additional time and space needed, is proportional to the derivation length in the original program. This overhead may increase space complexity, but does not change the worst-case time complexity.
The most commonly used formats for exchanging musical information today are limited in that they represent music as flat and rigid streams of events or as raw audio signals without any structural information about the...
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The most commonly used formats for exchanging musical information today are limited in that they represent music as flat and rigid streams of events or as raw audio signals without any structural information about the content. Such files can only be listened to in a linear way and reused and manipulated in manners determined by a target application such as a Digital Audio Workstation. The publisher has no means to incorporate their intentions or understanding of the content. This article introduces an extension of the music formalism CHARM for the representation of modifiable and reusable musical content on the Web. It discusses how various kinds of multi-hierarchical graph structures together with logical constraints can be useful to model different musical situations. In particular, we focus on presenting solutions on how to interpret, navigate and schedule such structures in order for them to be played back. We evaluate the versatility of the representation in a number of practical examples created with a Web-based implementation based on Semantic Web technologies.
Creation of customized animated 3D content is an important issue in web-based VR/AR environments that involve users with various requirements for the content, e.g., in education, training, tourism, cultural heritage a...
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Creation of customized animated 3D content is an important issue in web-based VR/AR environments that involve users with various requirements for the content, e.g., in education, training, tourism, cultural heritage and e-commerce. 3D content customization is a complex task, as it typically covers various content features such as geometry, structure and appearance. Although a number of tools enable modeling of 3D animations, they do not support on-demand animation customization to users' requirements specified using semantic (application or domain-specific) concepts. Available solutions permit creation of 3D content in its final form, require technical knowledge and skills or are limited to a particular application domain, without possibilities to easily change the target application or domain. In this paper, we present a pipeline for creation of customized animated 3D content on the web. The pipeline uses rule-based representation of 3D content activities, which are composed into more complex animations. Animation composition is performed on-demand, using queries describing requirements in an arbitrary application domain. The use of knowledge representation adapts the approach to the current trends in the evolution of the web, including the semantic web. It enables exploration by reasoning on the content generated with users' queries. Furthermore, it permits inference of tacit properties of animations from explicitly specified properties, thereby liberating the authors from specifying all necessary animation properties. The pipeline leverages an advanced motion capture system, 3D modeling tools and game engines. We have implemented and evaluated a web-based environment for on-demand animation composition. The proposed approach can be successfully used in multiple application areas on the web, in which 3D content components are intensively reconfigured according to requirements of different users.
This paper introduces argumentation over defeasible preferences in Arg2P, an argumentation framework based on logic programming. A computational mechanism is first implemented in Arg2P according to Dung's defeasib...
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