In this paper a variant of transition P systems with external
output designed to compute partial functions on natural numbers is
presented. These P systems are stable under composition, iteration and
unbounded minimization (μ–recursion) of functions. We prove that every
partial recursive function can be computed by such P systems, from
which the computational completeness of this model can be deduced.Ministerio de Ciencia y Tecnología TIC2002-04220-C03-0