“…In a series of papers (Rehof and Urzyczyn, 2011;Rehof and Urzyczyn, 2012;Düdder, Martens, Rehof, and Urzyczyn, 2012;Düdder, Martens, and Rehof, 2013;Bessai, Chen, et al, 2018), we have laid the theoretical foundations for understanding algorithmic and complexity of decidable inhabitation in subsystems of the intersection type system by Coppo and Dezani-Ciancaglini, 1980. In contrast to standard combinatory logic, where a fixed basis of combinators is usually considered, the inhabitation problem considered here is relativized to an arbitrary environment given as part of the input.…”