An Abelian Rule for BCI—and Variations
Tomasz Kowalski, Lloyd Humberstone · Notre Dame Journal of Formal Logic · 2016
We show the admissibility for BCI of a rule form of the characteristic implicational axiom of abelian logic, this rule taking us from (α→β)→β to α. This is done in Section 8, with surrounding sections exploring the admissibility and derivability of various related rules in several extensions of BCI.