
theorem :: Clique36a:
for R being non empty RelStr, a1,a2 being Element of R
 st a1 <> a2 & {a1,a2} is Clique of R holds a1 <= a2 or a2 <= a1
proof
let R be non empty RelStr, a1,a2 be Element of R;
   assume A1: a1 <> a2;
A2: a1 in {a1,a2} & a2 in {a1,a2} by TARSKI:def 2;
   assume {a1,a2} is Clique of R;
   hence thesis by A2,A1,Th6;
end;
