
theorem Th33:
for X being set, x being set st x in X holds {x} in CompleteSGraph X
proof
  let X be set, x be set such that
A1: x in X;
A2: {x} c= X by A1,ZFMISC_1:31;
A3: card {x} = 1 by CARD_1:30;
  thus {x} in CompleteSGraph X by A3,A2;
end;
