Communication P systems with channel states (CC P systems, for short) are a class of distributed parallel computing models, where communication (symport/antiport) rules associated with channel states are executed in a sequential manner on membrane channels. In this work, communication P systems with channel states working in flat maximally parallel manner are considered and the computational power is investigated. Specifically, it is proved that communication P systems with channel states using symport rules of length two are Turing universal when having one membrane and any number of channel states, or two membranes and three channel states. Furthermore, membrane division is introduced into communication P systems with channel states, communication P systems with channel states and membrane division (CCD P systems, for short) are proposed. We provide a uniform solution to the Hamiltonian path problem (HPP) by CCD P systems working in a flat maximally parallel manner.

Cell-like P systems with symport/antiport rules (CSA P systems, for short) are a class of computational models in membrane computing, inspired by the way of transmembrane transport of substances through membrane channels between neighboring regions in a cell. In this work, we propose a variant of C SA P systems, called cell-like P systems with symport/antiport rules and promoters (CSAp P systems, for short), where symport/antiport rules are regulated by multisets of promoters. The computational power of CSAp P systems is investigated. Specifically, it is proved that CSAp P systems working in the maximally parallel mode, having arbitrary large number of membranes and promoters and using only symport rules of length 1 or antiport rules of length 2, are able to compute only finite sets of non-negative integers. Furthermore, we show that CSAp P systems with two membranes working in a sequential mode when having at most two promoters and using only symport rules of length 2, or having at most one promoter and using symport rules of length 1 and antiport rules of length 2, are Turing universal.

Spiking neural (SN, for short) P systems are a class of distributed parallel computing models inspired by the way in which neurons communicate with each other by means of electrical impulses. Recently, a new variant of SN P systems, called SN P systems with homogenous neurons and synapses (HRSSN P systems for short) was proposed, where the spiking and forgetting rules are placed on synapses instead of in neurons and each synapse has the same set of spiking and forgetting rules. This variant of SN P systems has already been proved to be Turing universal as both number generating and accepting devices. In this work, we consider the problem of looking for small universal HRSSN P systems. Specifically, a universal HRRSN P system with standard rules and weight at most 5 having 70 neurons is constructed as a device of computing functions; as a number generator, we find a universal system with standard rules and weight at most 5 having 71 neurons.