Using Methods of Declarative Logic Programming for Intelligent

The Journal of Logic Programming, 1992

Proceeding of the 2007 …, 2007

1999

Most of the work conducted so far in the field of logic programming has focused on representing static knowledge, i.e. knowledge that does not evolve with time. To overcome this limitation, in a recent paper, the authors introduced the concept of dynamic logic programming. There, they studied and defined the declarative and operational semantics of sequences of logic programs (or dynamic logic programs), P0 ⊕...⊕Pn. Each such program contains knowledge about some given state, where different states may, e.g., represent different time periods or different sets of priorities. The role of dynamic logic programming is to employ relationships existing between the possibly mutually contradictory sequence of programs to precisely determine, at any given state, the declarative and procedural semantics of their combination. But how, in concrete situations, is a sequence of logic programs built? For instance, in the domain of actions, what are the appropriate sequences of programs that represent the performed actions and their effects? Whereas dynamic logic programming provides a way for determining what should follow, given the sequence of programs, it does not provide a good practical language for the specification of updates or changes in the knowledge represented by successive logic programs. In this paper we define a language designed for specifying changes to logic programs (LUPS - “Language for dynamic updates”). Given an initial knowledge base (in the form of a logic program) LUPS provides a way for sequentially updating it. The declarative meaning of a sequence of sets of update actions in LUPS is defined using the semantics of the dynamic logic program generated by those actions. We also provide a translation of the sequence of update statements sets into a single generalized logic program written in a meta-language, so that the stable models of the resulting program correspond to the previously defined declarative semantics. This meta-language is used in the actual implementation, although his is not the subject of this paper. Finally we briefly mention related work (lack of space prevents us from presenting more detailed comparisons).

1995

This paper proposes an update language, called ULL, for knowledge systems based on logic programming. This language is built upon two basic update operators, respectively denoting insertion and deletion of a positive literal (atom). Thus, simple control structures are defined for combining the basic updates into programs capable of expressing complex updates. The semantics of the update language is centered around the idea of executing a basic update by directly modifying the truth valuation of that (intensionally or extensionally defined) atom which is the object of the update. This modification propagates recursively to the truth valuations of those atoms dependent upon the updated one. The expressive power of this language is discussed, its implementation is studied, and an interpreter is given, which is proven correct w.r.t, the defined formal semantics. The computational complexity of the proposed implementation is also analyzed, showing that the update language interpreter runs efficiently. Finally, three extensions to ULL are discussed. The first allows the programmer to insert and delete rules, the second supports a form of hypothetical reasoning about updates, and the last introduces facilities in the language for the definition and the calling of update procedures. <1

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 2011

Action languages have gained popularity as a means for declaratively describing planning domains. This paper overviews two action languages, the Boolean language B and its multi-valued counterpart B M V . The paper analyzes some of the issues in using two alternative logic programming approaches (Answer Set Programming and Constraint Logic Programming over Finite Domains) for planning with B and B M V specifications. In particular, the paper provides an experimental comparison between these alternative implementation approaches.

2001

Recently, several approaches for updating knowledge bases represented as logic programs have been proposed. We present a generic framework for declarative specifications of update policies, which is built upon such approaches. It extends the LUPS language for update specifications, and incorporates the notion of events into the framework. An update policy allows an agent to flexibly react upon new information, arriving as an event, and perform suitable changes of its knowledge base. The framework compiles update policies to logic programs by means of generic translations, and can be instantiated in terms of different concrete update approaches. It thus provides a flexible tool for designing adaptive reasoning agents.

The Journal of Logic Programming, 2000

We introduce a logic programming language which supports hypothetical and counterfactual reasoning. The language is based on a conditional logic which enables to formalize conditional updates of the knowledge base. Due to the presence of integrity constraints, alternative revisions of the knowledge base may result from an update. We develop an abductive semantics which captures dierent evolutions of the knowledge base. Furthermore, we provide a goal-directed abductive proof procedure to compute the alternative solutions for a goal. We ®nally analyze our conditional programming language in the context of belief revision theory, and we establish a connection with Nebel's prioritized base revision.

Journal of Logic Language and Information

Reasoning about change is a central issue in research on human and robot planning. We study an approach to reasoning about action and change in a dynamic logic setting and provide a solution to problems which are related to the frame problem. Unlike most work on the flame problem the logic described in this paper is monotonic. It (implicitly) allows for the occurrence of actions of multiple agents by introducing non-stationary notions of waiting and test. The need to state a large number of "frame axioms" is alleviated by introducing a concept of chronological preservation to dynamic logic. As a side effect, this concept permits the encoding of temporal properties in a natural way. We compare the relative merits of our approach and non-monotonic approaches as regards different aspects of the frame problem. Technically, we show that the resulting extended systems of propositional dynamic logic preserve (weak) completeness, finite model property and decidability.

ALP Newsletter, 2001

The research group at CENTRIA UNL in Lisbon, in collaboration with Ferrara and Linköping, has been quite active in the field of Logic Programming (LP) geared towards rational agents over several years, and has investigated a spate of rational agent functionalities and their implementations. In particular, the Lisbon group has been active in the fields of learning, abduction, updating, argumentation, paraconsistency, belief revision, soft LP, contradicition removal, diagnosis, and debugging1. These research directions are all included in the ...

Lecture Notes in Computer Science, 2004

We acknowledge support by the Information Society Technologies programme of the European Commission, Future and Emerging Technologies under the IST-2001-37004 WASP project.

Encyclopedia of Information Science and Technology, Fourth Edition, 2018

In what seem to be never-ending quests for automation, integration, seamlessness, new genres of applications, and “smart systems”, all of which are fueled in part by technological changes, intellectual maturity (or so one thinks), and out-of-the-box thinking that says “surely, there must be a better way”, one dreams of a future. This paper suggests that logic programs employing recent advances in semantics and in knowledge representation formalisms provide a more robust framework in which to develop very intelligent systems in any domain of knowledge or application. The author has performed work applying this paradigm and these reasoning formalisms in the areas of financial applications, security applications, and enterprise information systems.

2000

Abstract The paper discusses an architecture for intelligent agents based on the use of A-Prolog-a language of logic programs under the answer set semantics. A-Prolog is used to represent the agent's knowledge about the domain and to formulate the agent's reasoning tasks. We outline how these tasks can be reduced to answering questions about properties of simple logic programs and demonstrate the methodology of constructing these programs. Keywords: Intelligent agents, logic programming and nonmonotonic reasoning.

Formal Approaches to Agent-Based …, 2002

In this paper we address the task of organising multi-agent systems in order to collectively solve problems. We base our approach on a logical model of rational agency comprising a few simple, but powerful, concepts. While many other researchers have tackled this problem using formal logic, the important aspect of the work described here is that the logical descriptions of the agents are directly executable using the Concurrent MetateM framework, allowing the execution of agents described in a combination of temporal, belief and ability logics. Here, we are particularly concerned with exploring some of the possible logical constraints that may be imposed upon these agents, and how these constraints affect the ability of the agents to come together to collectively solve problems.

DALI is a logic programming agent-oriented language defined in [1,2,3,4], fully formalized in [5,6]. DALI is fully implemented, and has been used in practice in a variety of applications [7,8,9,10]. A stable release of the DALI interpreter is publicly available at [11]. For the definition of DALI we have built under many respects upon our past work about meta-reasoning and reflection in logic programming languages [12,13,14,15,16]. In this work in particular, issues related to meta-level representation of predicates, atoms and rules are discussed in depth.

Computational …, 2007

The concept of an agent is increasingly used in contemporary software applications, particularly those involving the Internet, autonomous systems, or cooperation. However, with dependability and safety in mind, it is vital that the mechanisms for representing and implementing agents are clear and consistent. Hence there has been a strong research effort directed at using formal logic as the basis for agent descriptions and agent implementation. Such a logical basis not only presents the clarity and consistency required but also allows for important techniques such as logical verification to be applied.