Counterpart-based Quantified Temporal Logics

The aim of this work is to present counterpart-based quantified temporal logics from several points of view. We start by introducing a set-based semantics for a (first-order) linear temporal logic based on the counterpart paradigm, along with results on its positive normal form both in the case of partial functions and of (possibly duplicating) relations. Then, a categorical semantics of the logic is introduced by means of relational presheaves. Both the presentations of the logic via the positive normal form and its categorical semantics are formalised using the proof assistant Agda, and we highlight the crucial aspects of our implementation and the practical use of (quantified) temporal logics in a constructive proof assistant.