Compositional representation of rational functions
Tero Harju, H. C. M. Kleijn, Michel Latteux · RAIRO - Theoretical Informatics and Applications · 1992
The rational functions are shown to coincide with the compositions of endmarkings, morphisms and inverses of injective morphisms. To represent a rational function τ we need one endmarking µm, two morphisms α1, α3 and one inverse of an injective morphism α2 and then τ = µmα1α −1 2 α3.