let R1, R2 be Relation of (I *); ( ( for p, q being I -valued FinSequence holds
( [p,q] in R1 iff ( p c< q or ex k being Nat st
( k in dom p & k in dom q & [(p . k),(q . k)] in R & ( for n being Nat st 1 <= n & n < k holds
p . n = q . n ) ) ) ) ) & ( for p, q being I -valued FinSequence holds
( [p,q] in R2 iff ( p c< q or ex k being Nat st
( k in dom p & k in dom q & [(p . k),(q . k)] in R & ( for n being Nat st 1 <= n & n < k holds
p . n = q . n ) ) ) ) ) implies R1 = R2 )
assume that
A1:
for p, q being I -valued FinSequence holds
( [p,q] in R1 iff ( p c< q or ex k being Nat st
( k in dom p & k in dom q & [(p . k),(q . k)] in R & ( for n being Nat st 1 <= n & n < k holds
p . n = q . n ) ) ) )
and
A2:
for p, q being I -valued FinSequence holds
( [p,q] in R2 iff ( p c< q or ex k being Nat st
( k in dom p & k in dom q & [(p . k),(q . k)] in R & ( for n being Nat st 1 <= n & n < k holds
p . n = q . n ) ) ) )
; R1 = R2
let p, q be Element of I * ; RELSET_1:def 2 ( ( not [p,q] in R1 or [p,q] in R2 ) & ( not [p,q] in R2 or [p,q] in R1 ) )
( [p,q] in R1 iff ( p c< q or ex k being Nat st
( k in dom p & k in dom q & [(p . k),(q . k)] in R & ( for n being Nat st 1 <= n & n < k holds
p . n = q . n ) ) ) )
by A1;
hence
( ( not [p,q] in R1 or [p,q] in R2 ) & ( not [p,q] in R2 or [p,q] in R1 ) )
by A2; verum