Definition. Compositionality, computability, and complexity › Input complexity (§ 5) [pagin2021-input-complexity]

Let s be a normal term.

The term complexity CtR(s) of s relative to R is the length of the shortest derivation from some input term μ(t) to s.

The input complexity CRi(k) is the maximal CtR(s) where s has size k.