Set logics and their representations

Dion M. F. Hartmann

The subject of this thesis is on the shared horizon of theoretical physics and logic: Quantum logic. In 1936, Birkhofff and von Neumann already formulated a quantum logic. But, this logic has some undesirable properties concerning the interpretation of the logical conjunction and disjunction as ``and'' and ``or''. Therefor, Landsman has recently set out to develop a new logic for quantum mechanics, which is set up inside a topos and thus is intuitionistic. \n\nThe construction of Landsmans intuitionistic quantum logic relies on the Gelfand representation theorem. However, to apply the theorem a constructive proof is needed. Coquand and Spitters recently published such a proof, but the material that was published is too condensed for our taste. So in this thesis we attempt to expand on this constructive proof of the Gelfand representation theorem and check all details the original authors left out. As a result, more insight is gained in the constructive proof of the Gelfand representation theorem, providing a stronger foundation for intuitionistic quantum logic.

Hirokazu Nishimura

Heinrich Saller

Shen Jun, Junde Wu

In 2006, Gudder [Math. Slovaca 56, 573 (2006)] introduced a logic order ≼ on bounded quantum observable set S(H). In 2007, Pulmannova and Vincekova [Math Slovaca 57, 589 (2007)] proved that for each subset D of S(H), the infimum of D exists with respect to the logic order ≼. In 2008, Liu and Wu [J. Math. Phys. 49, 073521 (2008)] found a representation of the infimum A∧B for A,B∊S(H), and by using the limit methods, they gave out a representation for the infimum of D. But, that representation is complicated. In this paper, we present a simpler spectral representation for the infimum of D with respect to the logic order ≼.

Weihua Liu, Junde Wu

In 2006, Gudder introduced a logic order on the bounded quantum observable set S(H). In 2007, Pulmannova and Vincekova proved that for each subset D of S(H), the infimum of D exists with respect to this logic order. In this paper, we present a representation theorem for the infimum of D.

Giulia Battilotti, Rosapia Lauro Grotto

A crucial issue both in cognitive and psychoanalytical theories deals with the origin of mental representations. In order to explore this issue, the paper analyzes a pre-logical setting, by considering a formalized approach to the foundations of psychoanalysis in logic, interpreting and integrating the views by Freud, Matte Blanco, Klein and Bion. The formalized approach derives from a quantum model of spin states. A representation of the spin state of a particle in first order logic is abstracted to get a modality interpretable as an abstract projector. The last can be decomposed into a positive, negative and irreal component. The irreal component cannot emerge and, in logic, is absorbed by the two others, giving rise to logical duality. Due to its treatment of undefiniteness and coherence, the paper is meant to contribute to quantum cognition, in its particular sense of affective quantum cognition.