reserve X,Y,Z for set,
  a,b,c,d,x,y,z,u for object,
  R for Relation,
  A,B,C for Ordinal;
reserve H for Function;
reserve f,g for Function;
reserve M for non empty set;

theorem :: WAYBEL35:1, AK, 21.02.2006
  for X being set holds RelIncl X is_transitive_in X
proof
  let X be set;
  RelIncl X is transitive & field RelIncl X = X by Def1;
  hence thesis;
end;
