theorem
  w1 in Lin{w1,w2,w3} & w2 in Lin{w1,w2,w3} & w3 in Lin{w1,w2,w3}
proof
A1: w3 in {w1,w2,w3} by ENUMSET1:def 1;
  w1 in {w1,w2,w3} & w2 in {w1,w2,w3} by ENUMSET1:def 1;
  hence thesis by A1,RLVECT_3:15;
end;
