generators.tdTransducer:
  (
    { a:2, b:2, S:0 },
    { F:6, G:3, p:0 },
    { q },
    { 
      q[a[x1,x2]] -> F[q[x1],q[x1],q[x2],q[x2],q[x1],q[x1]],
      q[b[x1,x2]] -> G[q[x2],q[x1],q[x1]],
      q[S] -> p
    },
    q
  )
