Ticket Entailment is decidable

摘要

We prove the decidability of the logic T_→ of Ticket Entailment. This issue was first raised by Anderson and Belnap within the framework of relevance logic, and is equivalent to the question of the decidability of type inhabitation in simply typed combinatory logic with the partial basis BB'IW. We solve the equivalent problem of type inhabitation for the restriction of simply typed lambda calculus to hereditarily right-maximal terms.