Luděk Cienciala

P colonies and their extensions

P colonies are one of the variants of computational devices based on independent membrane agents, which are evolved and acting in a shared environment. P colonies belong to the family of models of membrane computing called P systems. We show that P colonies with capacity three and two agents using homogeneous programs without checking rules are computationally complete as well as eco-P colonies with two agents and a passive environment and PCol automata working in init mode.

Modularity in p colonies with checking rules

P colony, which was introduced in [9], is an abstract computing device composed of independent agents, acting and evolving in a shared environment. In this paper we bring a new view to investigation of the behavior of the P colonies. The first part of the paper focuses on the modularity of the P colonies with checking rules. We group the agents into modules with specific function. In the second part of the paper we introduce improved results concerning the computational power of the P colonies with capacity one.

Tissue p systems with cell separation: upper bound by PSPACE

Tissue P systems are a class of bio-inspired computing models motivated by biochemical interactions between cells in a tissue-like arrangement. This organization is formally described by an interaction graph with membranes at its vertices. Membranes communicate by exchanging objects from a finite set. This basic model was enhanced with the operation of cell separation, resulting in tissue P systems with cell separation. Uniform families of tissue P systems were recently studied. Their computational power was shown to range between P and NP&∪co&−NP, characterizing borderlines between tractability and intractability by length of rules and some other features. Here we show that the computational power of these uniform families in polynomial time is limited from above by the class PSPACE. In this way we relate the information-processing potential of bio-inspired tissue-like systems to classical parallel computing models as PRAM or alternating Turing machine.

Membrane automata with priorities

In this paper the one-way P automata with priorities are introduced. Such automata are P systems where the membranes are only allowed to consume objects from parent membranes, under the given conditions. The result of computation of these systems is the set of multiset sequences consumed by skin membrane into the system. The rules associated in some order with each membrane, cannot modify any objects, they can only move them through membrane. We show that P automata with priorities and two membranes can accept every recursively enumerated language.

P Colonies with Evolving Environment

We study two variants of P colonies with dynamic environment changing due to an underlying 0L scheme: P colonies with two objects inside each agent that can only consume objects, and P colonies with one object inside each agent which uses rewriting and communication rules. We show that the first kind of P colonies with one consumer agent can generate all sets of natural numbers computed by partially blind register machines. The second kind of P colonies with two agents with rewriting/communication rules is computationally complete. Finally, we demonstrate that P colonies with one such agent with checking programs can simulate catalytic P systems with one catalyst, and consequently, another relation to partially blind register machines is established.

Computational power of cell separation in tissue P systems

Abstract The paper focuses on the relation between biological and computational information processing. Several simple biological operations, as the exchange of molecules via cellular membrane or the cellular growth and separation, are abstracted into a mathematical model called membrane system (P system). This paper studies tissue P systems where a fixed interaction graph defines the communication between various types of cells. Polynomially uniform families of tissue P systems with the operation of cell separation were recently studied. Their computational power in polynomial time was shown to range between P and NP ∪ co - NP , characterizing borderlines between tractability and intractability by the length of rules controlling the interchange of objects. Here, we show that the computational power of these uniform families is limited by the class PSPACE , which is the class characterizing the power of classical parallel computing models, such as PRAM or the alternating Turing machine.

2D P colonies

We continue the investigation of P colonies introduced in [4], a class of abstract computing devices composed of independent agents, acting and evolving in a shared environment. We are introducing 2D P colonies with a 2D environment where the agents are located. Agents have limited information about the contents of the environment where they can move in four directions. To present computations of 2D P colonies we construct a simulation environment.

A class of restricted P colonies with string environment

In this paper we continue the study of variants of P colonies, called APCol systems, where the environment is given as a string and the model is an accepting system. We develop the concept by introducing the notion of the generating working mode. We then compare the power of a special subclass of APCol systems working in the generating mode to the power of register machines and context-free matrix grammars without appearance checking.

The Abilities of P Colony Based Models in Robot Control

P colonies were introduced in 2004 (see [10]) as an abstract computing device composed of independent single membrane agents, reactively acting and evolving in a shared environment. Each agent is equipped with a set of rules which are structured into simple programs. There are some models based on from original P colony. In most cases, models are equipped with such components which are associated with the environment. This is the case of Pcol automaton too. The agents work not only with environment but also with an input tape. We use this two theoretical computational devices to build complex robot controllers. In this paper we introduce simple controllers; the first one is used for fulfilling instructions and the other one for passing the maze using right-hand rule. We followed two different approaches and ideas and we present the obtained results in this paper.

P Colonies Processing Strings

In this paper we introduce and study P colonies where the environment is given as a string. These constructs, called automaton-like P colonies or APCol systems, behave like automata: during functioning, the agents change their own states and process the symbols of the string. We show that the family of e-free languages accepted by jumping finite automata is properly included in the family of languages accepted by APCol systems with one agent and any e-free recursively enumerable language can be obtained as a projection of a language accepted by an automaton-like P colony with two agents.