NOT logic

David Ellerman

Classical logic is usually interpreted as the logic of propositions. But from Boole's original development up to modern categorical logic, there has always been the alternative interpretation of classical logic as the logic of subsets of any given (non-empty) universe set. Partitions on a universe set are dual to subsets of a universe set in the sense of the reverse-the-arrows category-theoretic duality–which is reflected in the duality between quotient objects and subobjects throughout algebra. Hence the idea arises of a dual logic of partitions. That dual logic is described here. Partition logic is at the same mathematical level as subset logic since models for both are constructed from (partitions on or subsets of) arbitrary unstructured sets with no ordering relations, compatibility or accessibility relations, or topologies on the sets. Just as Boole developed logical finite probability theory as a quantitative treatment of subset logic, applying the analogous mathematical steps to partition logic yields a logical notion of entropy so that information theory can be refounded on partition logic. But the biggest application is that when partition logic and the accompanying logical information theory are ‘lifted’ to complex vector spaces, then the mathematical framework of quantum mechanics (QM) is obtained. Partition logic models the indefiniteness of QM while subset logic models the definiteness of classical physics. Hence partition logic may provide the backstory so the old idea of ‘objective indefiniteness’ in QM can be fleshed out to a full interpretation of quantum mechanics. In that case, QM will be the ‘killer application’ of partition logic.

Valerie Jamieson

AUGUST STERN

AUGUST STERN

Part 1 Infophysics: logic states logic superposition principle normal ordering Fermion logic logic density matrix logic equations of motion logic interference logic quarks Fibonacci numbers as logic quantum numbers appendix. Part 2 The intelligence code: imaginary logic quantum circuits logic exponent function dual codes quantum errors.

John J. Stachel

One can and often does use the word ‘logic’ in a variety of metaphorical ways, speaking of “the logic of the situation”, “the logic of events”, “the logic of history”, and so on. No harm is done, so long as one realizes that these usages are metaphorical, and should not be given any deeper significance – at least without extensive discussion of the meaning of the word ‘logic’ in these phrases. In this metaphorical sense, one may speak of “the logic of quantum mechanics”, just as one may speak of “the logic of modern art”, for example. But if we want to use the term ‘logic’ in a non-metaphorical sense – and I take it that this is the intent in all serious discussions of ‘quantum logic’–we are under some obligation to give an account of the significance to be given to the word ‘logic’ and to demonstrate that the proposed usage does not do violence to the several-thousand-year-old tradition in the field.

James Francis Burke