Papers by Gabriel Ciobanu
International Journal of Computers Communications & Control, 2010
Membrane systems are computing devices inspired from the cell functioning. A feature of membrane ... more Membrane systems are computing devices inspired from the cell functioning. A feature of membrane systems is the fact that objects and membranes are persistent. In fact, this is not quite true in the real world: cells and intracellular proteins have a well-defined lifetime. Inspired from these biological facts, we define a model of membrane systems in which each membrane and each object has attached a lifetime. Some results show that this model is at least as powerful as the usual one.
Nano Communication Networks, 2015
We use membrane systems to define a formalism inspired by cell biology in which mobility and timi... more We use membrane systems to define a formalism inspired by cell biology in which mobility and timing are explicitly specified. In order to reason about the behaviours of complex biological systems, we introduce several observational equivalences over mobile membranes with lifetimes. These equivalences based on observations correspond to several combinations of mobility operations that can be performed, timing aspects of the objects involved in mobility and their explicit positions inside membranes. Various relationships between these observational equivalences are proved. Moreover, we use the ambient logic to provide a logical characterization for located observational equivalence.
Given a P system Î with active membranes having several membranes, we construct a P system Î f ha... more Given a P system Î with active membranes having several membranes, we construct a P system Î f having only one membrane and rules involving catalysts, cooperation and priorities. The evolution of this "flat" P system Î f simulates the evolution of initial P system with active membranes Î by replacing any rule that changes the configuration in Î by prioritized rules application in a configuration of Î f .
In this paper we provide algorithms for solving the SAT problem using P systems with active membr... more In this paper we provide algorithms for solving the SAT problem using P systems with active membranes with neither polarization nor division rules. The semiuniform solutions are given under the assumption that initial configurations (either alphabet or structure) of exponential size are pre-computed by well-defined P systems (P systems with replicated rewriting and P systems with active membranes and membrane creation, respectively) working in polynomial time. An important observation is that we specify how the pre-computed initial configurations are constructed.
We introduce and study a multiset-based type system with ratio thresholds motivated by an importa... more We introduce and study a multiset-based type system with ratio thresholds motivated by an important regulatory mechanism inside a cell which try to maintain a "life-death" ratio between some given lower and upper thresholds. We use such a type system to control ratio thresholds in a bio-inspired and multisets-based formalism. For this type system we prove a subject reduction theorem, together with soundness and completeness theorems. A type inference for deducing the type of a system is presented.
Temporal logic of actions is a logic for specifying and reasoning about concurrent systems, devel... more Temporal logic of actions is a logic for specifying and reasoning about concurrent systems, developed mainly for verification. Ambient calculus is a formalism for describing mobility and distributed computation. We express mobile ambients in temporal logic of actions, provide some results and illustrate the description through examples. Finally we give an implementation of mobile ambients in temporal logic of actions that can be used for the verification of their behaviour.
Lecture Notes in Computer Science, 2012
In this paper we present a version of mobile ambients, called parMA, having a weak form of replic... more In this paper we present a version of mobile ambients, called parMA, having a weak form of replication and a parallel semantics. We investigate how parMA can solve intractable problems in a polynomial number of computational steps. We use parMA to give a semiuniform solution to a well-known strong NP-complete problem, namely to the Boolean satisfiability problem (SAT).
On the Computability Power of Membrane Systems with Controlled Mobility
Lecture Notes in Computer Science, 2012
ABSTRACT In a previous paper we have shown that membrane systems with controlled mobility are abl... more ABSTRACT In a previous paper we have shown that membrane systems with controlled mobility are able to solve a ΠP2 complete problem. Then, an enriched model with forced endocytosis and forced exocytosis enables us to move to the fourth level in the polynomial hierarchy, the model having ΣP4∪ΠP4 as lower bound. In this paper we study the computability power of this model (using forced endocytosis and forced exocytosis), and determine the border condition for achieving computational completeness: 4 membranes provide Turing completeness, while 3 membranes do not. Moreover, we show that the restricted division operation (which is crucial in achieving the ΣP4∪ΠP4 lower bound) does not provide computational completeness. However, Turing completeness can be achieved with pairs of operations (exocytosis, inhibitive endocytosis) and (inhibitive exocytosis, endocytosis) by using 4 membranes. Finally, we present some computability results expressing that membrane systems which use the operations of restricted division, restricted exocytosis and inhibitive endocytosis cannot yield computational completeness.
Formal Techniques for Networked and Distributed Systems – FORTE 2008, 2008
Ambient calculus is a calculus for mobile computing able to express local communications inside h... more Ambient calculus is a calculus for mobile computing able to express local communications inside hierarchical domains. So far the timing properties have not been considered in the framework of mobile ambients. We add timers to capabilities and ambients, and provide an operational semantics of the new calculus. Certain results are related to the passage of time, and some new behavioural equivalences over timed mobile ambients are defined. Timeout for network communication (TTL) can be naturally modelled by the time constraints over capabilities and ambients. The new formalism can be used to describe network protocols; Simple Network Management Protocol (SNMP) may implement its own strategy for timeout and retransmission in TCP/IP.
Lecture Notes in Computer Science
We investigate the problem of reaching a configuration from another configuration in mobile membr... more We investigate the problem of reaching a configuration from another configuration in mobile membranes, and prove that the reachability can be decided by reducing it to the reachability problem of a version of pure and public ambient calculus without the capability open.
Behavioural Types Inspired by Cellular Thresholds
Lecture Notes in Computer Science, 2014
The sodium-potassium exchange pump is a transmembrane transport protein that establishes and main... more The sodium-potassium exchange pump is a transmembrane transport protein that establishes and maintains the appropriate internal concentrations of sodium and potassium ions in cells. This exchange is an important physiological process; it is critical in maintaining the osmotic balance of the cell. Inspired by the functioning of this pump, we introduce and study a threshold-based type system in a bio-inspired formalism. Such a system can avoid errors in the definition of the formal model used to model certain biologic processes. For this type system we prove a subject reduction theorem.
Simple, Enhanced and Mutual Mobile Membranes
Lecture Notes in Computer Science, 2009
The operations governing the movement of biological membranes are endocytosis and exocytosis. New... more The operations governing the movement of biological membranes are endocytosis and exocytosis. New models of computation are inspired by these biological operations. In this paper we present the models defined by simple, enhanced and mutual mobile membranes, together with their biological motivations. Some results concerning their computational power are presented, including the first universality result for mutual mobile membranes. In
Lecture Notes in Computer Science, 2013
Mobile membranes represent a variant of membrane systems in which the main operations are inspire... more Mobile membranes represent a variant of membrane systems in which the main operations are inspired by the biological operations of endocytosis and exocytosis. We study the computational power of mobile membranes, proving an optimal computability result: three membranes are enough to have the same computational power as a Turing machine. Regarding the computational complexity, we present a semiuniform polynomial solution for a strong NP-complete problem (SAT problem) by using only endocytosis, exocytosis and elementary division.
Real-Time Migration Properties of rTiMo Verified in Uppaal
Software Engineering and Formal Methods, 2013
ABSTRACT This paper extends the TiMo family by introducing a real-time version named rTiMo. The r... more ABSTRACT This paper extends the TiMo family by introducing a real-time version named rTiMo. The rTiMo processes are able to move between different locations of a distributed environment, and communicate locally with other processes. Real-time constraints are used to control migration and communication in a real-time distributed system. In order to verify several properties of complex mobile systems described in rTiMo, we establish a relationship between rTiMo networks and a class of timed safety automata. The relationship allows the verification of temporal properties of real-time migrating processes using Uppaal capabilities. In particular, we check whether certain configurations are reached, and that certain timing constraints hold for an entire complex evolution.
Computational Power of Protein Interaction Networks
Lecture Notes in Computer Science, 2013
ABSTRACT It is proved that an abstract model of protein-protein interaction derived from membrane... more ABSTRACT It is proved that an abstract model of protein-protein interaction derived from membrane computing can simulate all computable functions by using a small number of components, not so complex proteins (having at most lengths two, where length is an abstract measure of complexity), and operations inspired by endocytosis (pino, phago) and exocytosis (exo).
Behavioural Equivalences in Real-Time P Systems
Lecture Notes in Computer Science, 2014
ABSTRACT
A Temporal Logic for Mutual Mobile Membranes with Objects on Surface
Lecture Notes in Computer Science, 2011
ABSTRACT
Formal Techniques for Distributed Systems, 2012
The temporal evolution of mobile processes is governed by independently operating local clocks an... more The temporal evolution of mobile processes is governed by independently operating local clocks and their migration timeouts. We define a formalism modelling such distributed systems allowing (maximal) parallel execution at each location. Taking into account explicit timing constraints based on migration and interprocess communication, we introduce and study a number of timed behavioural equivalences, aiming to provide theoretical underpinnings of verification methods. We also investigate relationships between such behavioural equivalences.
Lecture Notes in Computer Science, 2009
The mutual mobile membrane systems represent a variant of mobile membrane systems in which the en... more The mutual mobile membrane systems represent a variant of mobile membrane systems in which the endocytosis and exocytosis work whenever the involved membranes "agree" on the movement (this agreement is described by using dual objects a and a in the involved membranes). We study the computational power of this variant of mobile membrane systems, proving that only three membranes are enough to get the same computational power as a Turing machine.
Structural Properties and Observability in Membrane Systems
We assimilate some notions of the ambient calculus into the formalism of membrane systems. Thus w... more We assimilate some notions of the ambient calculus into the formalism of membrane systems. Thus we consider the exhibit of an ambient, its level, the structural congruence, and the contextual bisimulation to define and study in mobile membrane systems the corresponding observation barbs, the depths of a membrane system, and the structural congruence. The relation between these notions is given by a translation function.
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Papers by Gabriel Ciobanu