The tcc paradigm is a formalism for timed concurrent constraint
programming. Several tcc languages differing in their way of expressing
infinite behaviour have been proposed in the literature. In this paper we
study the expressive power of some of these languages. In particular, we show
- recursive procedures with parameters can be
encoded into parameterless recursive procedures with dynamic scoping, and
- replication can be encoded into parameterless
recursive procedures with static scoping, and vice-versa.
languages from (1) are strictly more expressive than the languages from (2).
Furthermore, we show that behavioural equivalence is
undecidable for the languages from (1), but decidable for the languages from
(2). The undecidability result holds even if the process variables take
values from a fixed finite domain