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This paper proposes an uniform framework for the proof theory of tractable approximations of propositional reasoning. The key idea is the introduction of approximate proofs. This makes possible the development of an approximating sequent calculus for propositional deduction where proofs can be sound, complete or multi-directional approximations of classical logic. We show how this calculus subsumes...
We investigate the epistemological properties of MKNF, Lifschitz's logic of minimal knowledge and negation as failure. In particular, we show that the expressive power of MKNF is equivalent to Moore's autoepistemic logic (AEL), by defining an embedding of MKNF into AEL and vice versa. We also prove that the negation as failure modality not of MKNF exactly corresponds to the negative introspection...
The IFT (Information Filtering Tool) project has the goal of developing new approaches to information filtering which are based on user modeling techniques for building and managing the representation of the user information preferences. In this paper we describe three prototypes which have been developed and evaluated within the project. All of them are dealing with textual semistructured documents...
The aim of the paper is to formally relate logical Horn models and Bayesian Networks (BNs) in the framework of diagnostic reasoning. This is pursued by pointing out similarities between the two formalisms at the modeling level and by introducing into BNs a suitable notion of derivation. We also discuss modeling issues underlying the choice of Horn-based models vs BNs, by making explicit the “completion...
Behaviour protocols are often used to coordinate the action of a group of two or more agents by limiting the nature of the agents' goals and the possibility of backtracking in the negotiation. The solution presented in this paper achieves the maximum flexibility because the negotiation itself is object of the planning activity. We extend the reasoning mechanism with the introduction of the...
Roles may be analyzed in many ways: “abstract agents”; as power positions; as sets of obligations; etc. For sure one of the main facets of roles is their Delegation-Adoption nature. This is exactly the perspective we assume here: it is a partial view of roles, but a fundamental one. In this paper we try to analyze a role just as a special kind of task-delegation, or contract. We recapitulate...
Traditionally spacecraft operations are automated by increasing the levels of automation in the ground segment. Certain missions, however, are only possible with high levels of on-board automation and autonomy with respect to the ground. These include missions to distant planets and bodies for which the light or radio signal travel time is too long to accommodate real time control and where the spacecraft...
In this paper, we propose and evaluate the use of an incomplete backtracking strategy for solving job shop scheduling problems with non-relaxable deadlines and complex metric constraints. Previous research in constraint satisfaction scheduling [4] has developed highly effective, heuristics for this class of problems based on simple measures of temporal sequencing flexibility. However, they are not...
This paper presents theoretical results and techniques for representing and managing task network goals in the framework of partial order planning. Task oriented formalisms are more expressive than partial order based formalism for problem goals in dynamical and changing domains, but they are not more powerful. We prove that it is always possible to express a task network problem in terms of an equivalent...
In this paper we present SAX, a system that generates hypertext descriptions of conceptual models designed with the SADT methodology. The combination of natural language and hypertext significantly lowers the communicative barrier between the analyst and the domain expert, thus increasing the effectiveness of conceptual model validation. The application of hybrid techniques for text generation guarantees...
This paper describes how hypermedia instruction manuals can be generated from a discourse plan: intentional and rhetorical knowledge in the plan tree are employed to construct the hypermedia elements, to assemble them into pages and to introduce links among them. Plan tree transformation functions are defined so as to ensure that generated hypermedia respect interface usability and Web design criteria...
We present a prototype of the Italian version of WordNet, a general computational lexical resource. Some relevant extensions are discussed to make it usable for parsing: in particular we add verbal selectional restrictions to make lexical discrimination effective. Italian WordNet has been coupled with a parser and a number of experiments have been performed to individuate the methodology with the...
FW-rules is a Prolog library which provides efficient support for forward (reactive) rules in Prolog. The library is based on an indexing mechanism to achieve efficiency, it supports interoperability between the forward chaining language and the underlying Prolog engine, and it can be embedded in any Prolog application. The implementation is based on a runtime support written in C to perform indexing...
This paper describes an analyst-oriented approach to conceptual knowledge representation and reasoning based on description logics. The approach is introduced to model and analyse the static part of behavioural concepts used in application domains. Behaviours are captured in a parametric way with respect to the description logic which corresponds to the structural modelling language. Structural concepts...
In this paper we consider two aspects of reasoning about action and change: qualification and ramification problems in the context of domain constraint axioms. It was pointed out that the same axiom may cause qualification and ramification. The reason that we distinguish these two cases lies in the semantics of concerning fluents. To distinguish whether a given constrain axiom involves qualification...
In this paper, we focus our attention on Representation of Linguistic Negation of Nuanced Properties in Knowledge-Based Systems. Our Approach is based upon a Similarity Relation between Nuanced Properties through their corresponding Fuzzy Sets. By using an interactive Choice Strategy, the User can explain the intended meaning of Linguistic Negations. This Model improves the abilities in Knowledge...
CBET is a software tool for the interactive exploration of a case base. CBET is an integrated environment that provides a range of browsing and display functions that make possible knowledge extraction from a set of cases. CBET is motivated by an application to training firemen. Here cases describe past forest fire fighting interventions and CBET is used to detect dependencies between data, acquire...
k-Nearest Neighbour is a popular case retrieval technique in Case-Based Reasoning. It has the disadvantage that its accuracy depends strongly on the weights assigned to the case features. This problem can be addressed by using Introspective Learning to discover appropriate values for feature weights. The basic idea with Introspective Learning (IL) is to examine cases that are similar in...
CompAss is a system which assists the students in the task of producing a plan of study. CompAss can be seen as an instance of a general tool for developing configuration applications running on the Web. Starting from a declarative description of the basic items to be chosen for the configuration and of the configuration constraints, the tool generates the HTML files for user guidance and the Java...
It has been shown that human experience and intelligence are extensively used during the phase of measurement validation and therefore an approach for representing them seems to be promising. The tests performed so far demonstrate an overall resolution capacity higher than mathematical approaches, more strict formally, but less easy to be mastered by the expert, though a quantitative and systematic...
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