for S1, S2 being non empty non void ManySortedSign
for X being V2() ManySortedSet of the carrier of S2
for f being Function of the carrier of S1, the carrier of S2
for g being Function st f,g form_morphism_between S1,S2 holds
for o being OperSymbol of S1
for p being Element of Args (o,(FreeMSA (X * f)))
for q being FinSequence st q = (hom (f,g,X,S1,S2)) # p holds
((hom (f,g,X,S1,S2)) . (the_result_sort_of o)) . ([o, the carrier of S1] -tree p) = [(g . o), the carrier of S2] -tree q