Substructural fixed-point theorems and the diagonal argument: theme and variations

10/01/2021

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by   David Michael Roberts, et al.

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This article re-examines Lawvere's abstract, category-theoretic proof of the fixed-point theorem whose contrapositive is a `universal' diagonal argument. The main result is that the necessary axioms for both the fixed-point theorem and the diagonal argument can be stripped back further, to a semantic analogue of a weak substructural logic lacking weakening or exchange.