Normal Bisimulation for Higher Order Pi-Calculus with Unguarded Choice

In this paper, we present a normal bisimulation for higher order pi-calculus with unguarded choice and prove the coincidence between such normal bisimulation and context bisimulation for higher order π-calculus with unguarded choice. To achieve this aim, we introduce indexed higher order π-calculus with unguarded choice. Furthermore we present corresponding indexed bisimulations in this calculus, and prove the equivalence between indexed context bisimulation and indexed normal bisimulation. As an application of this result, we prove the equivalence between context bisimulation and normal bisimulation for higher order π-calculus with unguarded choice.