“…As an example, let us consider the abstract program B 1 →J(1, 2, 2), 2 →J(1, 2, 2) . We can prove that the computation under B with the configuration σ (1 →0, 2 →1) converges, while it diverges with τ (1 →0, 2 →0); both the proofs are immediate, the second one is by coinduction 9 :…”