2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/219816We give a characterization, in terms of Galois infinite comatrix corings, of the corings that decompose as a direct sum of left comodules which are finitely generated as left modules. Then we show that the associated rational functor is exact. This is the case of a right semiperfect coring which is locally projective and whose Galois comodule is a projective left unital module with superfluous radical.Rings and AlgebrasCategory Theorytext