Nonlinear Counterfactuals

This repository contains an Isabelle/HOL formalisation of David Lewis' Counterfactual Operators from his 1973 Book Counterfactuals. It also formalises improved versions of Lewis Operators as introduced through Finkbeiner and Siber in their 2023 paper "Counterfactuals Modulo Temporal Logics". Furthermore it contains an formalisation of CTL*, performing a comparison between CTL*s expressive power and the expressive power of the counterfactual Would operator.

• Document: https://johanneshauschild.github.io/NonlinearCounterfactuals/NLC/Nonlinear_Counterfactuals/document.pdf
• Browsable theory: https://johanneshauschild.github.io/NonlinearCounterfactuals/NLC/Nonlinear_Counterfactuals/index.html