We provide alternative proofs and algorithms for results
proved by Sénizergues on rational and recognizable free
group languages. We consider two different approaches to the basic
problem of deciding recognizability for rational free group languages
following two fully independent paths: the symmetrification
method (using techniques inspired by the study of
inverse automata and inverse monoids) and
the right stabilizer method (a general approach generalizable to other
classes of
groups). Several different algorithmic characterizations of
recognizability are obtained, as well as other decidability results.