let S1, S2 be non empty transitive strict SubCatStr of C; :: thesis: ( the carrier of S1 = the carrier of C & the Arrows of S1 cc= the Arrows of C & ( for o1, o2 being object of C
for m being Morphism of o1,o2 holds
( m in the Arrows of S1 . (o1,o2) iff ( <^o1,o2^> <> {} & <^o2,o1^> <> {} & m is iso ) ) ) & the carrier of S2 = the carrier of C & the Arrows of S2 cc= the Arrows of C & ( for o1, o2 being object of C
for m being Morphism of o1,o2 holds
( m in the Arrows of S2 . (o1,o2) iff ( <^o1,o2^> <> {} & <^o2,o1^> <> {} & m is iso ) ) ) implies S1 = S2 )

assume that
A73: the carrier of S1 = the carrier of C and
A74: the Arrows of S1 cc= the Arrows of C and
A75: for o1, o2 being object of C
for m being Morphism of o1,o2 holds
( m in the Arrows of S1 . (o1,o2) iff ( <^o1,o2^> <> {} & <^o2,o1^> <> {} & m is iso ) ) and
A76: the carrier of S2 = the carrier of C and
A77: the Arrows of S2 cc= the Arrows of C and
A78: for o1, o2 being object of C
for m being Morphism of o1,o2 holds
( m in the Arrows of S2 . (o1,o2) iff ( <^o1,o2^> <> {} & <^o2,o1^> <> {} & m is iso ) ) ; :: thesis: S1 = S2
now
let i be set ; :: thesis: ( i in [: the carrier of C, the carrier of C:] implies the Arrows of S1 . i = the Arrows of S2 . i )
assume A79: i in [: the carrier of C, the carrier of C:] ; :: thesis: the Arrows of S1 . i = the Arrows of S2 . i
then consider o1, o2 being set such that
A80: ( o1 in the carrier of C & o2 in the carrier of C ) and
A81: i = [o1,o2] by ZFMISC_1:84;
reconsider o1 = o1, o2 = o2 as object of C by A80;
thus the Arrows of S1 . i = the Arrows of S2 . i :: thesis: verum
proof
thus the Arrows of S1 . i c= the Arrows of S2 . i :: according to XBOOLE_0:def 10 :: thesis: the Arrows of S2 . i c= the Arrows of S1 . i
proof
let n be set ; :: according to TARSKI:def 3 :: thesis: ( not n in the Arrows of S1 . i or n in the Arrows of S2 . i )
assume A82: n in the Arrows of S1 . i ; :: thesis: n in the Arrows of S2 . i
the Arrows of S1 . i c= the Arrows of C . i by A73, A74, A79, ALTCAT_2:def 2;
then reconsider m = n as Morphism of o1,o2 by A81, A82;
A83: m in the Arrows of S1 . (o1,o2) by A81, A82;
then A84: m is iso by A75;
( <^o1,o2^> <> {} & <^o2,o1^> <> {} ) by A75, A83;
then m in the Arrows of S2 . (o1,o2) by A78, A84;
hence n in the Arrows of S2 . i by A81; :: thesis: verum
end;
let n be set ; :: according to TARSKI:def 3 :: thesis: ( not n in the Arrows of S2 . i or n in the Arrows of S1 . i )
assume A85: n in the Arrows of S2 . i ; :: thesis: n in the Arrows of S1 . i
the Arrows of S2 . i c= the Arrows of C . i by A76, A77, A79, ALTCAT_2:def 2;
then reconsider m = n as Morphism of o1,o2 by A81, A85;
A86: m in the Arrows of S2 . (o1,o2) by A81, A85;
then A87: m is iso by A78;
( <^o1,o2^> <> {} & <^o2,o1^> <> {} ) by A78, A86;
then m in the Arrows of S1 . (o1,o2) by A75, A87;
hence n in the Arrows of S1 . i by A81; :: thesis: verum
end;
end;
hence S1 = S2 by A73, A76, ALTCAT_2:26, PBOOLE:3; :: thesis: verum