Baaz, Matthias, and Richard Zach. 2022. Epsilon theorems in intermediate logics. The Journal of Symbolic Logic 87(2), pp. 682–720. DOI: 10.1017/jsl.2021.103. Open access. Any intermediate propositional logic (i.e., a logic including intuitionistic logic and contained in classical logic) can be extended to a calculus with epsilon- and tau-operators and critical formulas. For classical logic, this … Continue reading Epsilon theorems in intermediate logics

Elkind, Landon D. C., and Richard Zach. 2022. The Genealogy of ‘∨.’ The Review of Symbolic Logic, 1–38. DOI: 10.1017/S1755020321000587. forthcoming The use of the symbol ∨ for disjunction in formal logic is ubiquitous. Where did it come from? The paper details the evolution of the symbol ∨ in its historical and logical context. Some … Continue reading The genealogy of ‘∨’