I am reading a note at Page 63
ftp://ftp.math.ethz.ch/users/pink/FGS/CompleteNotes.pdf
It says whenever G$G$ is finite and flat over S$S$ the functor Hom(G,H)${\rm Hom}(G,H)$ is representable. But it does not give the proof or any references.
Can anybody help me with this question?