The paper builds on both a simply typed term system ${\cal PR}^\omega$ and a computation model on Scott domains via so-called parallel typed while programs (PTWP). The former provides a notion of partial primitive recursive functional on Scott domains $D_\rho$ supporting a suitable concept of parallelism. Computability on Scott domains seems to entail that Kleene's schema of higher type simultaneous course-of-values recursion (scvr) is not reducible to partial primitive recursion. So extensions ${\cal PR}^{\omega e}$ and PTWP $^e$ are studied that (...) are closed under scvr. The twist are certain type 1 Gödel recursors ${\cal R}_k$ for simultaneous partial primitive recursion. Formally, ${\cal R}_k\vec{g}\vec{H}xi$ denotes a function $f_i \in D_{\iota\to\iota}$ , however, ${\cal R}_k$ is modelled such that $f_i$ is finite, or in other words, a partial sequence. As for PTWP $^e$ , the concept of type $\iota\to\iota$ writable variables is introduced, providing the possibility of creating and manipulating partial sequences. It is shown that the PTWP $^e$ -computable functionals coincide with those definable in ${\cal PR}^{\omega e}$ plus a constant for sequential minimisation. In particular, the functionals definable in ${\cal PR}^{\omega e}$ denoted ${\cal R}^{\omega e}$ can be characterised by a subclass of PTWP $^e$ -computable functionals denoted ${\rm PPR}^{\omega e}$ . Moreover, hierarchies of strictly increasing classes ${\cal R}^{\omega e}_n$ in the style of Heinermann and complexity classes ${\rm PPR}^{\omega e}_n$ are introduced such that $\forall n\ge 0. {\cal R}^{\omega e}_n ={\rm PPR}^{\omega e}_n$ . These results extend those for ${\cal PR}^\omega$ and PTWP [Nig94]. Finally, scvr is employed to define for each type $\sigma$ the enumeration functional $E^\sigma$ of all finite elements of $D_\sigma$. (shrink)

We study a notion ofpartial primitive recursion (p.p.r.) including the concept ofparallelism in the context of partial continuous functions of type level one in the sense of [Krei], [Sco82], [Ers]. A variety of subrecursive hierarchies with respect top.p.r. is introduced and it turns out that they all coincide.