Majors of functions
Couceiro, Miguel; Lehtonen, Erkko
Order, 35 (2018), 233–246
We investigate the minor order of functions, focusing on upper covers and common upper bounds of pairs of functions. We show that two functions of arities m and n have a common upper bound if and only if they have a common lower bound, and if a common upper bound exists, then there is one of arity m + n ? 1. Moreover, we determine the possible essential arities of upper covers of functions.