Preliminary exploration on actions as updates

2000

Over the last years various semantics have been proposed for dealing with updates in the setting of logic programs. The availability of dierent semantics naturally raises the question of which are the most adequate to model updates. A systematic approach to face this question is to identify general principles against which such semantics should be tested. In this paper we

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, 2004

Over the last years various semantics have been proposed for dealing with updates of logic programs by (other) logic programs. Most of these semantics extend the stable models semantics of normal, extended (with explicit negation) or generalized (with default negation in rule heads) logic programs. In this paper we propose a well founded semantics for logic programs updates. We motivate our proposal with both practical and theoretical argumentations. Various theoretical results presented here show how our proposal is related to the stable model approach and how it extends the well founded semantics of normal and generalized logic programs.

2017

Logics of action, for reasoning about the effects of state change, and logics of belief, accounting for belief revision and update, have much in common. Furthermore, we may undertake an action because we hold a particular belief, and revise our beliefs in the light of observed consequences of an action. So studies of these two aspects are inevitably intertwined. However, we argue, a clear separation of the two is helpful in understanding their interactions. We give a semantic presentation of such a separation, introducing a semantic setting that supports one logic for describing the effects of actions, which are modeled as changing the values of particular atomic properties, or fluents, and another for expressing more complex facts or beliefs about the world. We use a simple state-logic, to account for state change, and show how it can be integrated with a variety of domain-logics, of fact or belief, for reasoning about the world. Stateand domain-logics are linked, syntactically and...

International Journal of Advanced Computer Science and Applications, 2012

In this paper, we present a general schema for defining new update semantics. This schema takes as input any basic logic programming semantics, such as the stable semantics, the p-stable semantics or the M M r semantics, and gives as output a new update semantics. The schema proposed is based on a concept called minimal generalized S models, where S is any of the logic programming semantics. Each update semantics is associated to an update operator. We also present some properties of these update operators.

2001

Abstract We consider the problem of how an agent's knowledge can be updated. We propose a formal method of knowledge update on the basis of the semantics of modal logic S5. In our method, an update is specified according to the minimal change on both the agent's actual world and knowledge. We then investigate the semantics of knowledge update and characterize several specific forms of knowledge update which have important applications in reasoning about change of agents' knowledge.

2011

Action languages have gained popularity as a means for declaratively describing planning domains. This paper overviews two action languages, the Boolean language BB and its multi-valued counterpart B MV B^ MV. 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 BB and B MV B^ MV specifications.

Workshops in Computing, 1995

It has been argued that some sort of control must be introduced in order to perform update operations in deductive databases see e.g. 1, 17. Indeed, many approaches rely on a procedural semantics of rule based languages and often perform updates as side-e ects. Depending on the evaluation procedure, updates are generally performed in the body top-down evaluation or in the head of rules bottom-up evaluation. We demonstrate that updates can be speci ed in a purely declarative manner using standard model based semantics without relying on procedural aspects of program evaluation. The key idea is to incorporate states as rst-class objects into the language. This is the source of the additional expressiveness needed to de ne updates. We i n troduce the update language Statelog +-, discuss various domains of application and outline how to implement computation of the perfect model semantics for Statelog +-programs.