let A, B be non empty transitive AltCatStr ; :: thesis: ( A,B have_the_same_composition iff for a1, a2, a3 being object of A st <^a1,a2^> <> {} & <^a2,a3^> <> {} holds
for b1, b2, b3 being object of B st <^b1,b2^> <> {} & <^b2,b3^> <> {} & b1 = a1 & b2 = a2 & b3 = a3 holds
for f1 being Morphism of a1,a2
for g1 being Morphism of b1,b2 st g1 = f1 holds
for f2 being Morphism of a2,a3
for g2 being Morphism of b2,b3 st g2 = f2 holds
f2 * f1 = g2 * g1 )

hereby :: thesis: ( ( for a1, a2, a3 being object of A st <^a1,a2^> <> {} & <^a2,a3^> <> {} holds
for b1, b2, b3 being object of B st <^b1,b2^> <> {} & <^b2,b3^> <> {} & b1 = a1 & b2 = a2 & b3 = a3 holds
for f1 being Morphism of a1,a2
for g1 being Morphism of b1,b2 st g1 = f1 holds
for f2 being Morphism of a2,a3
for g2 being Morphism of b2,b3 st g2 = f2 holds
f2 * f1 = g2 * g1 ) implies A,B have_the_same_composition )
assume A1: A,B have_the_same_composition ; :: thesis: for a1, a2, a3 being object of A st <^a1,a2^> <> {} & <^a2,a3^> <> {} holds
for b1, b2, b3 being object of B st <^b1,b2^> <> {} & <^b2,b3^> <> {} & b1 = a1 & b2 = a2 & b3 = a3 holds
for f1 being Morphism of a1,a2
for g1 being Morphism of b1,b2 st g1 = f1 holds
for f2 being Morphism of a2,a3
for g2 being Morphism of b2,b3 st g2 = f2 holds
f2 * f1 = g2 * g1

let a1, a2, a3 be object of A; :: thesis: ( <^a1,a2^> <> {} & <^a2,a3^> <> {} implies for b1, b2, b3 being object of B st <^b1,b2^> <> {} & <^b2,b3^> <> {} & b1 = a1 & b2 = a2 & b3 = a3 holds
for f1 being Morphism of a1,a2
for g1 being Morphism of b1,b2 st g1 = f1 holds
for f2 being Morphism of a2,a3
for g2 being Morphism of b2,b3 st g2 = f2 holds
f2 * f1 = g2 * g1 )

assume A2: ( <^a1,a2^> <> {} & <^a2,a3^> <> {} ) ; :: thesis: for b1, b2, b3 being object of B st <^b1,b2^> <> {} & <^b2,b3^> <> {} & b1 = a1 & b2 = a2 & b3 = a3 holds
for f1 being Morphism of a1,a2
for g1 being Morphism of b1,b2 st g1 = f1 holds
for f2 being Morphism of a2,a3
for g2 being Morphism of b2,b3 st g2 = f2 holds
f2 * f1 = g2 * g1

let b1, b2, b3 be object of B; :: thesis: ( <^b1,b2^> <> {} & <^b2,b3^> <> {} & b1 = a1 & b2 = a2 & b3 = a3 implies for f1 being Morphism of a1,a2
for g1 being Morphism of b1,b2 st g1 = f1 holds
for f2 being Morphism of a2,a3
for g2 being Morphism of b2,b3 st g2 = f2 holds
f2 * f1 = g2 * g1 )

assume that
A3: ( <^b1,b2^> <> {} & <^b2,b3^> <> {} ) and
A4: ( b1 = a1 & b2 = a2 & b3 = a3 ) ; :: thesis: for f1 being Morphism of a1,a2
for g1 being Morphism of b1,b2 st g1 = f1 holds
for f2 being Morphism of a2,a3
for g2 being Morphism of b2,b3 st g2 = f2 holds
f2 * f1 = g2 * g1

let f1 be Morphism of a1,a2; :: thesis: for g1 being Morphism of b1,b2 st g1 = f1 holds
for f2 being Morphism of a2,a3
for g2 being Morphism of b2,b3 st g2 = f2 holds
f2 * f1 = g2 * g1

let g1 be Morphism of b1,b2; :: thesis: ( g1 = f1 implies for f2 being Morphism of a2,a3
for g2 being Morphism of b2,b3 st g2 = f2 holds
f2 * f1 = g2 * g1 )

assume A5: g1 = f1 ; :: thesis: for f2 being Morphism of a2,a3
for g2 being Morphism of b2,b3 st g2 = f2 holds
f2 * f1 = g2 * g1

let f2 be Morphism of a2,a3; :: thesis: for g2 being Morphism of b2,b3 st g2 = f2 holds
f2 * f1 = g2 * g1

let g2 be Morphism of b2,b3; :: thesis: ( g2 = f2 implies f2 * f1 = g2 * g1 )
assume A6: g2 = f2 ; :: thesis: f2 * f1 = g2 * g1
A7: ( the Comp of A . a1,a2,a3 = the Comp of A . [a1,a2,a3] & the Comp of B . b1,b2,b3 = the Comp of B . [b1,b2,b3] ) by MULTOP_1:def 1;
( the Comp of A . a1,a2,a3 is Function of [:<^a2,a3^>,<^a1,a2^>:],<^a1,a3^> & <^a1,a3^> <> {} & the Comp of B . b1,b2,b3 is Function of [:<^b2,b3^>,<^b1,b2^>:],<^b1,b3^> & <^b1,b3^> <> {} ) by A2, A3, ALTCAT_1:def 4;
then ( dom (the Comp of A . a1,a2,a3) = [:<^a2,a3^>,<^a1,a2^>:] & dom (the Comp of B . b1,b2,b3) = [:<^b2,b3^>,<^b1,b2^>:] ) by FUNCT_2:def 1;
then A8: ( [f2,f1] in dom (the Comp of A . a1,a2,a3) & [g2,g1] in dom (the Comp of B . b1,b2,b3) ) by A2, A3, ZFMISC_1:def 2;
thus f2 * f1 = (the Comp of A . a1,a2,a3) . f2,f1 by A2, ALTCAT_1:def 10
.= (the Comp of B . b1,b2,b3) . g2,g1 by A1, A4, A5, A6, A7, A8, Th10
.= g2 * g1 by A3, ALTCAT_1:def 10 ; :: thesis: verum
end;
assume A9: for a1, a2, a3 being object of A st <^a1,a2^> <> {} & <^a2,a3^> <> {} holds
for b1, b2, b3 being object of B st <^b1,b2^> <> {} & <^b2,b3^> <> {} & b1 = a1 & b2 = a2 & b3 = a3 holds
for f1 being Morphism of a1,a2
for g1 being Morphism of b1,b2 st g1 = f1 holds
for f2 being Morphism of a2,a3
for g2 being Morphism of b2,b3 st g2 = f2 holds
f2 * f1 = g2 * g1 ; :: thesis: A,B have_the_same_composition
let a1, a2, a3, x be set ; :: according to PARTFUN1:def 6,YELLOW20:def 1 :: thesis: ( not x in (dom (the Comp of A . [a1,a2,a3])) /\ (dom (the Comp of B . [a1,a2,a3])) or (the Comp of A . [a1,a2,a3]) . x = (the Comp of B . [a1,a2,a3]) . x )
assume x in (dom (the Comp of A . [a1,a2,a3])) /\ (dom (the Comp of B . [a1,a2,a3])) ; :: thesis: (the Comp of A . [a1,a2,a3]) . x = (the Comp of B . [a1,a2,a3]) . x
then A10: ( x in dom (the Comp of A . [a1,a2,a3]) & x in dom (the Comp of B . [a1,a2,a3]) ) by XBOOLE_0:def 4;
then ( [a1,a2,a3] in dom the Comp of A & [a1,a2,a3] in dom the Comp of B ) by FUNCT_1:def 4, RELAT_1:60;
then A11: ( [a1,a2,a3] in [:the carrier of A,the carrier of A,the carrier of A:] & [a1,a2,a3] in [:the carrier of B,the carrier of B,the carrier of B:] ) by PARTFUN1:def 4;
then reconsider a1 = a1, a2 = a2, a3 = a3 as object of A by MCART_1:73;
reconsider b1 = a1, b2 = a2, b3 = a3 as object of B by A11, MCART_1:73;
A12: ( the Comp of A . a1,a2,a3 = the Comp of A . [a1,a2,a3] & the Comp of B . b1,b2,b3 = the Comp of B . [b1,b2,b3] ) by MULTOP_1:def 1;
then ( ( [:<^a2,a3^>,<^a1,a2^>:] <> {} implies <^a1,a3^> <> {} ) & ( [:<^b2,b3^>,<^b1,b2^>:] <> {} implies <^b1,b3^> <> {} ) ) by A10;
then A13: ( dom (the Comp of A . a1,a2,a3) = [:<^a2,a3^>,<^a1,a2^>:] & dom (the Comp of B . b1,b2,b3) = [:<^b2,b3^>,<^b1,b2^>:] ) by FUNCT_2:def 1;
then consider f2, f1 being set such that
A14: ( f2 in <^a2,a3^> & f1 in <^a1,a2^> & x = [f2,f1] ) by A10, A12, ZFMISC_1:def 2;
reconsider f2 = f2 as Morphism of a2,a3 by A14;
reconsider f1 = f1 as Morphism of a1,a2 by A14;
A15: ( f1 in <^b1,b2^> & f2 in <^b2,b3^> ) by A10, A12, A13, A14, ZFMISC_1:106;
reconsider g1 = f1 as Morphism of b1,b2 by A10, A12, A13, A14, ZFMISC_1:106;
reconsider g2 = f2 as Morphism of b2,b3 by A10, A12, A13, A14, ZFMISC_1:106;
(the Comp of A . [a1,a2,a3]) . x = (the Comp of A . a1,a2,a3) . f2,f1 by A14, MULTOP_1:def 1
.= f2 * f1 by A14, ALTCAT_1:def 10
.= g2 * g1 by A9, A14, A15
.= (the Comp of B . b1,b2,b3) . g2,g1 by A15, ALTCAT_1:def 10 ;
hence (the Comp of A . [a1,a2,a3]) . x = (the Comp of B . [a1,a2,a3]) . x by A14, MULTOP_1:def 1; :: thesis: verum