let R, P be Relation; ( R is asymmetric implies P /\ R is asymmetric )
assume
R is asymmetric
; P /\ R is asymmetric
then A1:
R is_asymmetric_in field R
by Def13;
A2:
field (P /\ R) c= (field P) /\ (field R)
by RELAT_1:19;
now let a,
b be
set ;
( a in field (P /\ R) & b in field (P /\ R) & [a,b] in P /\ R implies not [b,a] in P /\ R )assume that A3:
(
a in field (P /\ R) &
b in field (P /\ R) )
and A4:
[a,b] in P /\ R
;
not [b,a] in P /\ RA5:
[a,b] in R
by A4, XBOOLE_0:def 4;
(
a in field R &
b in field R )
by A2, A3, XBOOLE_0:def 4;
then
not
[b,a] in R
by A1, A5, Def5;
hence
not
[b,a] in P /\ R
by XBOOLE_0:def 4;
verum end;
then
P /\ R is_asymmetric_in field (P /\ R)
by Def5;
hence
P /\ R is asymmetric
by Def13; verum