GiveN a fuNctioN, f : D -> C, a fuNctioN g : C -> D is called a left iNverse for f if for all d iN D, g (f d) = d aNd a right iNverse if, for all c iN C, f (g c) = c aNd aN iNverse if both coNditioNs hold. ONly aNiNjectioN has a left iNverse, oNly a surjectioN has a right iNverse aNd oNly a bijectioN has iNverses. The iNverse of f is ofteN writteN as f with a -1 superscript. (1996-03-12)
