theorem aaa1: :: MSAFREE5:83

for S being non empty non void ManySortedSign
for s being SortSymbol of S
for X being non-empty ManySortedSet of the carrier of S
for x being Element of X . s
for t, t1 being Element of (Free (S,X)) st the_sort_of t1 = s holds
(t,[x,s]) <- t1 in the Sorts of (Free (S,X)) . (the_sort_of t)