Full Cut-Elimination for Stratified or Total Definitions

Prove full cut-elimination for the cyclic sequent calculus for non-monotone inductive definitions on sequents with stratified definitions, or, more broadly, on sequents with total definitions.

Background

The paper establishes a cut-restriction theorem for stratified definitions: every provable sequent can be proved using only elementary cuts of a specified form. Full cut-elimination is proved for the infinitary calculus on positive definitions but not for the cyclic calculus. The authors explicitly state that it is unresolved whether the cyclic cut-restriction result can be strengthened, possibly even for total definitions.

References

It is currently unknown whether Theorem \ref{thm:cut-restriction} can be strengthened to full cut-elimination.

— An Infinitary and a Cyclic Sequent Calculus for Non-Monotone Inductive Definitions  (2609.26337 - Eede, 22 Sep 2026) in Section 6, final paragraph of the section on Cut-Elimination