Refutation systems in modal logic

Complete deductive systems are constructed for the non-valid (refutable) formulae and sequents of some propositional modal logics. Thus, complete syntactic characterizations in the sense of Lukasiewicz are established for these logics and, in particular, purely syntactic decision procedures for them are obtained. The paper also contains some historical remarks and a general discussion on refutation systems.Presented byJan Zygmunt     

A note on the logic of signed equations

A signed -equation is an expression of the form t t or t t, where t and t are -terms (for some ranked set ). We characterize those classes of -algebras which are models of a set of signed -equations. Further we consider the problem of finding a complete deductive system analogous to equational logic for the logical consequence operation restricted to signed equations.     

A note on the measurement of conditional discrimination.

An analysis of some extreme forms of stimulus control that a simple conditional-discrimination procedure can generate leads to the conclusion that accuracy does not provide an orderly scale of measurement. Dependence on accuracy to evaluate a conditional discrimination, particularly at intermediate levels of accuracy, can generate erroneous conclusions about the extent to which the controlling relations are those specified by the experimenter.     

A note on conditional reflex studies of schizophrenia in France

In France, beginning with 1946, the method of Ivanov-Smolenski was used to study schizophrenia, but after 1957, sensory conditioning procedures have been employed (EEG sound-light, evoked potentials in children, SAE conditioning in adults) and more recently eye blink and operant conditioning).     

Syntactical results on the arithmetical completeness of modal logic

In this paper the PA-completeness of modal logic is studied by syntactical and constructive methods. The main results are theorems on the structure of the PA-proofs of suitable arithmetical interpretationsS of a modal sequentS, which allow the transformation of PA-proofs ofS into proof-trees similar to modal proof-trees. As an application of such theorems, a proof of Solovay's theorem on arithmetical completeness of the modal system G is presented for the class of modal sequents of Boolean combinations of formulas of the form p _i,m _i=0, 1, 2, ... The paper is the preliminary step for a forthcoming global syntactical resolution of the PA-completeness problem for modal logic.     

A note on the decidability of a strong relevant logic

A modified filtrations argument is used to prove that the relevant logic S of [2] is decidable.     

A note on the interpretability logic of finitely axiomatized theories

In [6] Albert Visser shows that ILP completely axiomatizes all schemata about provability and relative interpretability that are provable in finitely axiomatized theories. In this paper we introduce a system called ILP that completely axiomatizes the arithmetically valid principles of provability in and interpretability over such theories. To prove the arithmetical completeness of ILP we use a suitable kind of tail models; as a byproduct we obtain a somewhat modified proof of Visser's completeness result.Research supported by the Netherlands Organization for Scientific Research (NWO).     

A note on three-valued logic and Tarski theorem on truth definitions

We introduce a notion of semantical closure for theories by formalizing Nepeivoda notion of truth. [10]. Tarski theorem on truth definitions is discussed in the light of Kleene's three valued logic (here treated with a formal reinterpretation of logical constants). Connections with Definability Theory are also established.A first version was prepared for sec. 5-Gnsaga-CNR and presented at the Logic Seminar, Institute of Philosophy, University of Firenze, in the academic year 1978–79. The author would like to thank the referee for his criticism and the Alexander von Humboldt-Stiftung for the support during the revision of the paper.     

Physicalism,instrumentalism and the semantics of modal logic

The delicate point in the formalistic position is to explain how the non-intuitionistic classical mathematics is significant, after having initially agreed with the intuitionists that its theorems lack a real meaning in terms of which they are true (S. C. Kleene, 1952).