theorem Lm2:
  Perm(P,q) is with_fixpoint implies Perm(P,p=>q) is with_fixpoint
  proof
    given x being object such that
A1: x is_a_fixpoint_of Perm(P,q);
    reconsider xx=x as set by TARSKI:1;
    take SetVal(V,p) --> xx;
    thus thesis by A1,Th14;
  end;
