theorem Th36:
  (i <= n or i > 3*n) & i in dom f implies (Relax n).f.i=f.i
proof
  assume
A1: ( i <= n or i > 3*n)& i in dom f;
  thus (Relax n).f.i=Relax(f,n).i by Def15
    .=f.i by A1,Def14;
end;
