reserve n for Element of NAT,
  p,q,r,s for Element of HP-WFF;
reserve V for SetValuation;
reserve P for Permutation of V;

theorem Th37:
  for g being Function of SetVal(V,p), SetVal(V,q) holds Perm(P,p
  => q)".g = Perm(P,q)"*g*Perm(P,p)
proof
  let g be Function of SetVal(V,p), SetVal(V,q);
  thus Perm(P,p => q)".g = (Perm(P,p) => Perm(P,q))".g by Th35
    .= Perm(P,q)"*g*Perm(P,p) by Th25;
end;
