theorem
  i in dom p implies (p+*(i,m+1) in dom primrec(f1,f2,i) iff
  p+*(i,m) in dom primrec(f1,f2,i) &
  (p+*(i,m))^<*primrec(f1,f2,i).(p+*(i,m))*> in dom f2) by Lm6;
