Fuzzy Logic and Arithmetical Hierarchy,II

A very simple many-valued predicate calculus is presented; a completeness theorem is proved and the arithmetical complexity of some notions concerning provability is determined.     

The Undecidability of Iterated Modal Relativization

In dynamic epistemic logic and other fields, it is natural to consider relativization as an operator taking sentences to sentences. When using the ideas and methods of dynamic logic, one would like to iterate operators. This leads to iterated relativization. We are also concerned with the transitive closure operation, due to its connection to common knowledge. We show that for three fragments of the logic of iterated relativization and transitive closure, the satisfiability problems are fi1 ¹₁–complete. Two of these fragments do not include transitive closure. We also show that the question of whether a sentence in these fragments has a finite (tree) model is fi0 ⁰₁–complete. These results go via reduction to problems concerning domino systems.     

The Incompleteness of Theories of Games

We first state a few previously obtained results that lead to general undecidability and incompleteness theorems in axiomatized theories that range from the theory of finite sets to classical elementary analysis. Out of those results we prove several incompleteness theorems for axiomatic versions of the theory of noncooperative games with Nash equilibria; in particular, we show the existence of finite games whose equilibria cannot be proven to be computable.     

Modelling simultaneous games in dynamic logic

We make a proposal for formalizing simultaneous games at the abstraction level of player’s powers, combining ideas from dynamic logic of sequential games and concurrent dynamic logic. We prove completeness for a new system of ‘concurrent game logic’ CDGL with respect to finite non-determined games. We also show how this system raises new mathematical issues, and throws light on branching quantifiers and independence-friendly evaluation games for first-order logic.     

Dialogue Games for Many-Valued Logics — an Overview

An overview of different versions and applications of Lorenzen’s dialogue game approach to the foundations of logic, here largely restricted to the realm of manyvalued logics, is presented. Among the reviewed concepts and results are Giles’s characterization of ?ukasiewicz logic and some of its generalizations to other fuzzy logics, including interval based logics, a parallel version of Lorenzen’s game for intuitionistic logic that is adequate for finite- and infinite-valued Gödel logics, and a truth comparison game for infinite-valued Gödel logic.     

多值逻辑与语义赋值博弈

文章在扩展博弈上,给出了多值逻辑的语义赋值博弈的一般框架,避免了博弈者在多值逻辑的语义博弈中声明无穷对象的问题;然后通过Eloise赢的策略定义博弈的语义概念——赋值,证明了多值逻辑的博弈语义与Tarski语义是等价的;最后,根据语义赋值博弈框架对经典逻辑进行了博弈化。     

The expressibility of fragments of Hybrid Graph Logic on finite digraphs

Hybrid Graph Logic is a logic designed for reasoning about graphs and is built from a basic modal logic, augmented with the use of nominals and a facility to verify the existence of paths in graphs. We study the finite model theory of Hybrid Graph Logic. In particular, we develop pebble games for Hybrid Graph Logic and use these games to exhibit strict infinite hierarchies involving fragments of Hybrid Graph Logic when the logic is used to define problems involving finite digraphs. These fragments are parameterized by the quantifier-rank of formulae along with the numbers of propositional symbols and nominals that are available. We ascertain exactly the relative definability of these parameterized fragments of the logic.     

Three Complexity Problems in Quantified Fuzzy Logic

We prove that the sets of standard tautologies of predicate Product Logic and of predicate Basic Logic, as well as the set of standard-satisfiable formulas of predicate Basic Logic are not arithmetical, thus finding a rather satisfactory solution to three problems proposed by Hájek in [H01].     

Giles’s Game and the Proof Theory of Łukasiewicz Logic

In the 1970s, Robin Giles introduced a game combining Lorenzen-style dialogue rules with a simple scheme for betting on the truth of atomic statements, and showed that the existence of winning strategies for the game corresponds to the validity of formulas in Łukasiewicz logic. In this paper, it is shown that ‘disjunctive strategies’ for Giles’s game, combining ordinary strategies for all instances of the game played on the same formula, may be interpreted as derivations in a corresponding proof system. In particular, such strategies mirror derivations in a hypersequent calculus developed in recent work on the proof theory of Łukasiewicz logic. Presented by Daniele Mundici     

Game Logic and its Applications II

This paper provides a Genzten style formulation of the game logic framework GLm (0 m ), and proves the cut-elimination theorem for GLm. As its application, we prove the term existence theorem for GL used in Part I.     

Philosophy for Computers: Some Explorations in Philosophical Modeling

Philosophical modeling has a long and distinguished history, but the computer offers new and powerful prospects for the creation and manipulation of models. It seems inevitable that the computer will become a major tool in future philosophical research. Here I offer an overview of explorations in philosophical computer modeling that we in the Group for Logic and Formal Semantics at SUNY Stony Brook have undertaken: explorations regarding (1) the potential emergence of cooperation in a society of egoists, (2) self-reference and paradox in fuzzy logic, (3) a fractal approach to formal systems, and (4) on-going explorations with models for the emergence of communication. The attempt is not to give a detailed report on any of these but to give a bird s-eye view of them all, emphasizing the general form that the models take, the philosophical motivations behind them, and the kinds of philosophical results that they may have to offer.     

THE RELATION BETWEEN SCIENCE AND THEOLOGY: THE CASE FOR COMPLEMENTARITY REVISITED

Abstract. Donald MacKay has suggested that the logical concept of complementarity is needed to relate scientific and theological thinking. According to Ian Barbour, this concept should only be used within, not between, disciplines. This article therefore attempts to clarify that contrast from the standpoint of cognitive process. Thinking in terms of complementarity is explicated within a structuralist-genetic, interactive-constructivist, developmental theory of the neo- and post-Piagetian kind, and its role in religious development is indicated. Adolescents'complementary views on Creation and on the corresponding scientific accounts serve as an illustration. After further analysis of parallel and circular complementarity, it is shown under which conditions complementarity of science and theology can be better justified and may be potentially more fruitful than is apparent from Barbour's or even MacKay's considerations.     

Calling the beautiful game ugly: A response to Davis

In a previous article (Kretchmar 2005 Kretchmar, S. 2005. Game flaws. Journal of the Philosophy of Sport, XXXII(1): 36–48.  [Google Scholar]), I identified problems in a certain species of games and traced these harms to something I called a ‘game flaw’. Unfortunately, ‘the beautiful game’ is a member of that species. I say it is unfortunate because Paul Davis (2006 Davis, P. 2006. Game strengths. Journal of the Philosophy of Sport, XXXIII(1): 50–66.  [Google Scholar]), when taking me to task for providing an argument that, in his terms, was ‘not especially compelling’, focused on the game of soccer (hereafter, football). The issue over which we contended is one of ‘time management’– that is, how game initiation, duration and closure are structured. I suggest that two basic methods for managing such requirements are available. Games take place during a stipulated amount of time or for a specified number of events. In my original article, I identified four fundamental problems that may accompany time-regulated games. In this essay, I attempt to fortify those claims against Davis's criticisms.