Many unconventional computing models, including some that appear to be quite different from traditional ones such as Turing machines, happen to characterise either the complexity class P or PSPACE when working in deterministic polynomial time (and in the maximally parallel way, where this applies). We discuss variants of cellular automata and membrane systems that escape this dichotomy and characterise intermediate complexity classes, usually defined in terms of Turing machines with oracles, as well as some possible reasons why this happens.

翻译：许多非常规计算模型，包括一些看起来与传统模型（如图灵机）截然不同的模型，在确定性多项式时间内（以及在适用的情况下以最大并行方式）运行时，恰好刻画了复杂性类 P 或 PSPACE。我们讨论了细胞自动机和膜系统的几种变体，它们突破了这种二分法，刻画了中间复杂性类（通常由带预言机的图灵机定义），并探讨了产生这种现象的一些可能原因。