let S1, S2, E be non empty ManySortedSign ; :: thesis: for f1, g1, f2, g2 being Function st f1 tolerates f2 & f1,g1 form_morphism_between S1,E & f2,g2 form_morphism_between S2,E holds
f1 +* f2,g1 +* g2 form_morphism_between S1 +* S2,E

let f1, g1, f2, g2 be Function; :: thesis: ( f1 tolerates f2 & f1,g1 form_morphism_between S1,E & f2,g2 form_morphism_between S2,E implies f1 +* f2,g1 +* g2 form_morphism_between S1 +* S2,E )
assume that
A1: f1 tolerates f2 and
A2: ( dom f1 = the carrier of S1 & dom g1 = the carrier' of S1 ) and
A3: rng f1 c= the carrier of E and
B3: rng g1 c= the carrier' of E and
A4: f1 * the ResultSort of S1 = the ResultSort of E * g1 and
A5: for o being set
for p being Function st o in the carrier' of S1 & p = the Arity of S1 . o holds
f1 * p = the Arity of E . (g1 . o) and
A6: ( dom f2 = the carrier of S2 & dom g2 = the carrier' of S2 ) and
A7: ( rng f2 c= the carrier of E & rng g2 c= the carrier' of E ) and
A8: f2 * the ResultSort of S2 = the ResultSort of E * g2 and
A9: for o being set
for p being Function st o in the carrier' of S2 & p = the Arity of S2 . o holds
f2 * p = the Arity of E . (g2 . o) ; :: according to PUA2MSS1:def 13 :: thesis: f1 +* f2,g1 +* g2 form_morphism_between S1 +* S2,E
set f = f1 +* f2;
set g = g1 +* g2;
set S = S1 +* S2;
the carrier of (S1 +* S2) = the carrier of S1 \/ the carrier of S2 by CIRCCOMB:def 2;
hence dom (f1 +* f2) = the carrier of (S1 +* S2) by A2, A6, FUNCT_4:def 1; :: according to PUA2MSS1:def 13 :: thesis: ( dom (g1 +* g2) = the carrier' of (S1 +* S2) & rng (f1 +* f2) c= the carrier of E & rng (g1 +* g2) c= the carrier' of E & the ResultSort of (S1 +* S2) * (f1 +* f2) = (g1 +* g2) * the ResultSort of E & ( for b1 being set
for b2 being set holds
( not b1 in the carrier' of (S1 +* S2) or not b2 = the Arity of (S1 +* S2) . b1 or b2 * (f1 +* f2) = the Arity of E . ((g1 +* g2) . b1) ) ) )

A10: the carrier' of (S1 +* S2) = the carrier' of S1 \/ the carrier' of S2 by CIRCCOMB:def 2;
hence dom (g1 +* g2) = the carrier' of (S1 +* S2) by A2, A6, FUNCT_4:def 1; :: thesis: ( rng (f1 +* f2) c= the carrier of E & rng (g1 +* g2) c= the carrier' of E & the ResultSort of (S1 +* S2) * (f1 +* f2) = (g1 +* g2) * the ResultSort of E & ( for b1 being set
for b2 being set holds
( not b1 in the carrier' of (S1 +* S2) or not b2 = the Arity of (S1 +* S2) . b1 or b2 * (f1 +* f2) = the Arity of E . ((g1 +* g2) . b1) ) ) )

A11: the ResultSort of S1 +* the ResultSort of S2 = the ResultSort of (S1 +* S2) by CIRCCOMB:def 2;
( rng (f1 +* f2) c= (rng f1) \/ (rng f2) & (rng f1) \/ (rng f2) c= the carrier of E ) by A3, A7, FUNCT_4:18, XBOOLE_1:8;
hence rng (f1 +* f2) c= the carrier of E by XBOOLE_1:1; :: thesis: ( rng (g1 +* g2) c= the carrier' of E & the ResultSort of (S1 +* S2) * (f1 +* f2) = (g1 +* g2) * the ResultSort of E & ( for b1 being set
for b2 being set holds
( not b1 in the carrier' of (S1 +* S2) or not b2 = the Arity of (S1 +* S2) . b1 or b2 * (f1 +* f2) = the Arity of E . ((g1 +* g2) . b1) ) ) )

( rng (g1 +* g2) c= (rng g1) \/ (rng g2) & (rng g1) \/ (rng g2) c= the carrier' of E ) by B3, A7, FUNCT_4:18, XBOOLE_1:8;
hence rng (g1 +* g2) c= the carrier' of E by XBOOLE_1:1; :: thesis: ( the ResultSort of (S1 +* S2) * (f1 +* f2) = (g1 +* g2) * the ResultSort of E & ( for b1 being set
for b2 being set holds
( not b1 in the carrier' of (S1 +* S2) or not b2 = the Arity of (S1 +* S2) . b1 or b2 * (f1 +* f2) = the Arity of E . ((g1 +* g2) . b1) ) ) )

A12: ( rng the ResultSort of S1 c= the carrier of S1 & rng the ResultSort of S2 c= the carrier of S2 ) ;
A13: dom the ResultSort of E = the carrier' of E by FUNCT_2:def 1;
thus (f1 +* f2) * the ResultSort of (S1 +* S2) = (f1 * the ResultSort of S1) +* (f2 * the ResultSort of S2) by A1, A2, A6, A11, A12, FUNCT_4:73
.= the ResultSort of E * (g1 +* g2) by A4, A7, A8, A13, FUNCT_7:10 ; :: thesis: for b1 being set
for b2 being set holds
( not b1 in the carrier' of (S1 +* S2) or not b2 = the Arity of (S1 +* S2) . b1 or b2 * (f1 +* f2) = the Arity of E . ((g1 +* g2) . b1) )

let o be set ; :: thesis: for b1 being set holds
( not o in the carrier' of (S1 +* S2) or not b1 = the Arity of (S1 +* S2) . o or b1 * (f1 +* f2) = the Arity of E . ((g1 +* g2) . o) )

let p be Function; :: thesis: ( not o in the carrier' of (S1 +* S2) or not p = the Arity of (S1 +* S2) . o or p * (f1 +* f2) = the Arity of E . ((g1 +* g2) . o) )
assume A14: ( o in the carrier' of (S1 +* S2) & p = the Arity of (S1 +* S2) . o ) ; :: thesis: p * (f1 +* f2) = the Arity of E . ((g1 +* g2) . o)
A15: the Arity of S1 +* the Arity of S2 = the Arity of (S1 +* S2) by CIRCCOMB:def 2;
A16: ( dom the Arity of S1 = the carrier' of S1 & rng the Arity of S1 c= the carrier of S1 * & dom the Arity of S2 = the carrier' of S2 & rng the Arity of S2 c= the carrier of S2 * ) by FUNCT_2:def 1;
per cases ( o in the carrier' of S2 or not o in the carrier' of S2 ) ;
suppose A17: o in the carrier' of S2 ; :: thesis: p * (f1 +* f2) = the Arity of E . ((g1 +* g2) . o)
then A18: p = the Arity of S2 . o by A14, A15, A16, FUNCT_4:14;
then p in rng the Arity of S2 by A16, A17, FUNCT_1:def 5;
then p is FinSequence of the carrier of S2 by FINSEQ_1:def 11;
then rng p c= dom f2 by A6, FINSEQ_1:def 4;
then A19: ( dom (f1 * p) c= dom p & dom (f2 * p) = dom p ) by RELAT_1:44, RELAT_1:46;
thus (f1 +* f2) * p = (f1 * p) +* (f2 * p) by FUNCT_7:11
.= f2 * p by A19, FUNCT_4:20
.= the Arity of E . (g2 . o) by A9, A17, A18
.= the Arity of E . ((g1 +* g2) . o) by A6, A17, FUNCT_4:14 ; :: thesis: verum
end;
suppose A20: not o in the carrier' of S2 ; :: thesis: p * (f1 +* f2) = the Arity of E . ((g1 +* g2) . o)
then A21: o in the carrier' of S1 by A10, A14, XBOOLE_0:def 3;
A22: p = the Arity of S1 . o by A14, A15, A16, A20, FUNCT_4:12;
then p in rng the Arity of S1 by A16, A21, FUNCT_1:def 5;
then p is FinSequence of the carrier of S1 by FINSEQ_1:def 11;
then rng p c= dom f1 by A2, FINSEQ_1:def 4;
then A23: ( dom (f1 * p) = dom p & dom (f2 * p) c= dom p ) by RELAT_1:44, RELAT_1:46;
thus (f1 +* f2) * p = (f2 +* f1) * p by A1, FUNCT_4:35
.= (f2 * p) +* (f1 * p) by FUNCT_7:11
.= f1 * p by A23, FUNCT_4:20
.= the Arity of E . (g1 . o) by A5, A21, A22
.= the Arity of E . ((g1 +* g2) . o) by A6, A20, FUNCT_4:12 ; :: thesis: verum
end;
end;