2026-09-22 18:02:42
New pre-print out (and submitted to JFP): "niFite semPurtatoni" (Finite permutations in Agda). We study a first-order representation of finite permutations: every value of this type represents a bijection by construction (1st image). An interesting part is composition — finding a definition that's structurally recursive at all takes some care (2nd image: an example, plus the key lemma that `skip` and `pinch` are approximate inverses). Inversion, and the classical Lehmer-code &q…


