R.A. Kowalski. Logic without model theory. In D. Gabbay, editor, What is a logical system? Oxford University Press, 1995.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....in the context of program transformation and synthesis. In recent years, Robert Kowalski has revisited the equation, expressing that one should stress much more the procedural reading of logic programs, while reducing the emphasis on the declarative (in particular, the model theoretical) one ([13]) As an initial response to that, we cannot help wondering why Logic Programming would be better at expressing procedures than procedural programming languages themselves. In some cases, in which the procedures are given in terms of natural language sentences (such as in legal reasoning ....

R.A. Kowalski. Logic without model theory. In D. Gabbay, editor, What is a logical system? Oxford University Press, 1995.

....a ground representation must be used. For knowledge assimilation, the changes to the object program are normally global and permanent. Thus, in the case of knowledge assimilation, it is particularly important that no unnecessary changes are made and the new knowledge base remains consistent. In (Kowalski 1993), the problem of adding a statement S to the database D is discussed in detail. Four cases are described. 1. S is a logical consequence of D 2. D = D 1 [ D 2 and D 2 is a logical consequence of D 1 [ fSg. 3. S is inconsistent with D. 4. None of the relationships (1) 3) hold. It is assumed ....

Kowalski, R. A. (1993), Logic without model theory, Technical report, Department of Computing, Imperial College.

....them semiformal, because these representations may have a formal syntax, but often lack a formal semantics. There have been attempts to assign to these representations a formal semantics by mapping them to a formal language manually or automatically [Wing 90] We follow the correspondence theory [Kowalski 93] by mapping elements of external representations automatically to the internal formal representation. This mapping is reversible. Thus, though our external representations may and should give the impression of informality, they are in fact formal and have the same semantics as the internal ....

R. A. Kowalski, Logic without Model Theory, Technical Report, Imperial College, 1993

....rules which operate only upon the structural content of the logical expressions. Third, a DRS can be investigated from a more psychological point of view as a contribution of building up a mental model of a language user. The second and the third ways lead to the concept of knowledge assimilation [Kowalski 93] According to this proof theoretic approach a DRS is processed by resource constrained deduction and tested whether it can be added to a continuously changing theory. The terms truth and falsity of DRSs in model 9 theory are replaced by the proof of consistency and inconsistency in the ....

R. A. Kowalski, Logic without Model Theory, Technical Report, Imperial College, 1993

....seems punctual and very promising, following the line suggested by Kowalski to conceive [ a mental language in which an agent subjectively constructs internal representations of its experience and beliefs and uses those representations to derive logical consequences. R. Kowalski in [Kow94], our emphatization) ....

R. Kowalski. Logic without Model Theory. Journal of Logic and Computation, 1994.

....To achieve this goal, we have introduced visual and textual views of the program being constructed, e.g. transition networks for finite state machines and window oriented user interfaces. Furthermore, we have associated each view with an editor, and following Kowalski s correspondence theory [Kowalski 93] have provided an automatic bidirectional mapping between a program and its views. As will be explained below, we also added a repository of predefined application specific components. 3 Repository Predefined Components Program Textual View Visual View These design decisions have ....

R. A. Kowalski, Logic without Model Theory, Technical Report, Imperial College, 1993

....which operate only upon the structural content of the logical expressions. And third, a DRS can be investigated from a more psychological point of view as a contribution of building up a mental model of a language user. The second and the third ways lead to the concept of knowledge assimilation [Kowalski 93] In this proof theoretic account a DRS is processed by resourceconstrained deduction and tested whether it can be added to a continuously changing theory. The terms truth and falsity of DRSs in model theory are replaced by the proof of consistency and inconsistency in the process of knowledge ....

....specification language. 7.3 Knowledge Assimilation Specifications in controlled natural language are gradually composed by a user and translated into Prolog clauses. These Prolog clauses are currently simply added to a knowledge base. A more refined solution should employ knowledge assimilation [Kowalski 93] The knowledge base is considered as a (changing) theory of the domain in question. New information arrives confirming or refuting the current theory. Four cases have to be considered: The new Prolog clauses can be derived from the existing theory. In this case they are redundant, but the ....

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R.A. Kowalski, Logic without Model Theory, Technical Report, Imperial College, 1993

....be regarded as a sort of introspection. Of course, this description does not explain how the agent gets its goals (and intentions) in the first place. What happens if at some point the agent has no goal at all. Here is where, we believe, inputs from the environment play a key role. Kowalski [Kow94] has explained how observations can be assimilated by agents, generating new goals by using integrity constraints as condition action rules. Having accepted the necessity of mentalistic abstractions, such as goals and beliefs, in the analysis of agents, one then has the problem of how to ....

....due to their naturalness (descriptions are closer to natural language) However, the enriched semantics required by those languages (to accommodate the modal operators) inevitably introduces the omniscient agent problem 6 contradicting any attempt to model a realistic agent. Kowalski has argued [Kow94] that the real problem is that the notion of logical consequence, establishing what can be derived or deduced from what is, in those logics, disconnected from 6 An agent must know all the logical consequences of the knowledge it has. This is also known as Perfect Rationality. the ....

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Robert Kowalski. Logic without model theory. In Dov Gabbay, editor, What is a logical system?, chapter 2, pages 35--71. 1994. (Also at http://wwwlp. doc.ic.ac.uk/ lp/Kowalski/models.ps).

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