theorem Th23: :: MSAFREE5:82

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 t is x -omitting holds
(t,[x,s]) <- t1 = t