let IT1, IT2 be ManySortedFunction of (FreeEnv MSA),MSA; :: thesis: ( IT1 is_homomorphism FreeEnv MSA,MSA & ( for s being SortSymbol of S
for x, y being set st y in FreeSort the Sorts of MSA,s & y = root-tree [x,s] & x in the Sorts of MSA . s holds
(IT1 . s) . y = x ) & IT2 is_homomorphism FreeEnv MSA,MSA & ( for s being SortSymbol of S
for x, y being set st y in FreeSort the Sorts of MSA,s & y = root-tree [x,s] & x in the Sorts of MSA . s holds
(IT2 . s) . y = x ) implies IT1 = IT2 )

reconsider IT1' = IT1, IT2' = IT2 as ManySortedFunction of (FreeMSA the Sorts of MSA),MSA ;
assume IT1 is_homomorphism FreeEnv MSA,MSA ; :: thesis: ( ex s being SortSymbol of S ex x, y being set st
( y in FreeSort the Sorts of MSA,s & y = root-tree [x,s] & x in the Sorts of MSA . s & not (IT1 . s) . y = x ) or not IT2 is_homomorphism FreeEnv MSA,MSA or ex s being SortSymbol of S ex x, y being set st
( y in FreeSort the Sorts of MSA,s & y = root-tree [x,s] & x in the Sorts of MSA . s & not (IT2 . s) . y = x ) or IT1 = IT2 )

then A13: IT1' is_homomorphism FreeMSA the Sorts of MSA,MSA ;
assume A14: for s being SortSymbol of S
for x, y being set st y in FreeSort the Sorts of MSA,s & y = root-tree [x,s] & x in the Sorts of MSA . s holds
(IT1 . s) . y = x ; :: thesis: ( not IT2 is_homomorphism FreeEnv MSA,MSA or ex s being SortSymbol of S ex x, y being set st
( y in FreeSort the Sorts of MSA,s & y = root-tree [x,s] & x in the Sorts of MSA . s & not (IT2 . s) . y = x ) or IT1 = IT2 )

defpred S1[ set , set , set ] means $3 = root-tree [$2,$1];
A15: for s being SortSymbol of S
for x, y being set st y in FreeGen s,the Sorts of MSA holds
( (IT1' . s) . y = x iff S1[s,x,y] )
proof
let s be SortSymbol of S; :: thesis: for x, y being set st y in FreeGen s,the Sorts of MSA holds
( (IT1' . s) . y = x iff S1[s,x,y] )

let x, y be set ; :: thesis: ( y in FreeGen s,the Sorts of MSA implies ( (IT1' . s) . y = x iff S1[s,x,y] ) )
assume A16: y in FreeGen s,the Sorts of MSA ; :: thesis: ( (IT1' . s) . y = x iff S1[s,x,y] )
then y in (FreeSort the Sorts of MSA) . s ;
then A17: y in FreeSort the Sorts of MSA,s by MSAFREE:def 13;
consider a being set such that
A18: a in the Sorts of MSA . s and
A19: y = root-tree [a,s] by A16, MSAFREE:def 17;
thus ( (IT1' . s) . y = x implies y = root-tree [x,s] ) by A14, A17, A18, A19; :: thesis: ( S1[s,x,y] implies (IT1' . s) . y = x )
assume y = root-tree [x,s] ; :: thesis: (IT1' . s) . y = x
then [x,s] = [a,s] by A19, TREES_4:4;
then x = a by ZFMISC_1:33;
hence (IT1' . s) . y = x by A14, A17, A18, A19; :: thesis: verum
end;
assume IT2 is_homomorphism FreeEnv MSA,MSA ; :: thesis: ( ex s being SortSymbol of S ex x, y being set st
( y in FreeSort the Sorts of MSA,s & y = root-tree [x,s] & x in the Sorts of MSA . s & not (IT2 . s) . y = x ) or IT1 = IT2 )

then A20: IT2' is_homomorphism FreeMSA the Sorts of MSA,MSA ;
assume A21: for s being SortSymbol of S
for x, y being set st y in FreeSort the Sorts of MSA,s & y = root-tree [x,s] & x in the Sorts of MSA . s holds
(IT2 . s) . y = x ; :: thesis: IT1 = IT2
A22: for s being SortSymbol of S
for x, y being set st y in FreeGen s,the Sorts of MSA holds
( (IT2' . s) . y = x iff S1[s,x,y] )
proof
let s be SortSymbol of S; :: thesis: for x, y being set st y in FreeGen s,the Sorts of MSA holds
( (IT2' . s) . y = x iff S1[s,x,y] )

let x, y be set ; :: thesis: ( y in FreeGen s,the Sorts of MSA implies ( (IT2' . s) . y = x iff S1[s,x,y] ) )
assume A23: y in FreeGen s,the Sorts of MSA ; :: thesis: ( (IT2' . s) . y = x iff S1[s,x,y] )
then y in (FreeSort the Sorts of MSA) . s ;
then A24: y in FreeSort the Sorts of MSA,s by MSAFREE:def 13;
consider a being set such that
A25: a in the Sorts of MSA . s and
A26: y = root-tree [a,s] by A23, MSAFREE:def 17;
thus ( (IT2' . s) . y = x implies y = root-tree [x,s] ) by A21, A24, A25, A26; :: thesis: ( S1[s,x,y] implies (IT2' . s) . y = x )
assume y = root-tree [x,s] ; :: thesis: (IT2' . s) . y = x
then [x,s] = [a,s] by A26, TREES_4:4;
then x = a by ZFMISC_1:33;
hence (IT2' . s) . y = x by A21, A24, A25, A26; :: thesis: verum
end;
IT1' = IT2' from MSAFREE1:sch 3(A13, A15, A20, A22);
hence IT1 = IT2 ; :: thesis: verum