  We prove "untyping" theorems: in some typed theories (semirings, Kleene
algebras, residuated lattices, involutive residuated lattices), typed equations
can be derived from the underlying untyped equations. As a consequence, the
corresponding untyped decision procedures can be extended for free to the typed
settings. Some of these theorems are obtained via a detour through fragments of
cyclic linear logic, and give rise to a substantial optimisation of standard
proof search algorithms.
