reserve Y for non empty set;
reserve Y for non empty set;
reserve Y for non empty set;
reserve Y for non empty set,
  a,b,c,d,e,f,g for Function of Y,BOOLEAN;

theorem
  a '&' b '<' a 'or' b
proof
  a '&' b '<' a & a '<' a 'or' b by Lm1,Th38a;
  hence thesis by BVFUNC_1:15;
end;
