# Gabriel CiobanuRomanian Academy Iasi branch · Institute of Computer Science

Gabriel Ciobanu

Professor, senior researcher

## About

358

Publications

39,598

Reads

**How we measure 'reads'**

A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more

2,224

Citations

Citations since 2017

Introduction

Gabriel Ciobanu is a senior researcher at the Institute of Computer Science, Romanian Academy, and the editor-in-chief of the Scientific Annals of Computer Science. His research interests include Distributed Systems and Concurrency (process calculi), Theory of Programming (semantics, logics, formal methods) and Natural Computing (membrane systems). For his research he received important awards of the Romanian Academy of Sciences (in 2000, 2004, 2013). He is a member of Academia Europaea.

Additional affiliations

January 2008 - present

**Universitatea Alexandru Ioan Cuza**

September 2006 - present

**Scientific Annals of Computer Science**

Position

- Editor-in-Chief

January 2005 - present

## Publications

Publications (358)

We propose a typing system based on multiparty session types and probabilistic interactions. We define a probabilistic process calculus using nondeterministic external choices and probabilistic internal choices. Interval probability (a generalization of traditional probability using pairs of lower and upper probabilities) are used for global and lo...

We use the functional programming language Haskell to design semantic interpreters for the spiking neural P systems. Haskell provides an appropriate support for implementing the denotational semantics of a concurrent language inspired by the spiking neural P systems. This language and its semantics describe properly the structure and behaviour of t...

Natural sciences are influencing the area of information sciences, and the meaning of computation has been modified [...]

The theory of finitely supported structures is used for dealing with very large sets having a certain degree of symmetry. This framework generalizes the classical set theory of Zermelo-Fraenkel by allowing infinitely many basic elements with no internal structure (atoms) and by equipping classical sets with group actions of the permutation group ov...

We study the dynamics of information sharing in web-based social networks and analyse in a stochastic manner some aspects of this phenomenon. We define the stochastic sharing calculus by considering probabilistic factors and stochastic evolutions that could be analysed statistically. A rate-based operational semantics allows specific observations a...

This paper presents a calculus inspired by the spiking neural P systems. Its operational and denotational semantics are defined; they are related by using the metric semantics methodology, showing that the denotational semantics is correct with respect to the operational one. We use the continuations for concurrency to describe precisely the nondet...

The goal of this paper is to define and study the notion of infinity in the framework of finitely supported structures, presenting new properties of infinite cardinalities. Some of these properties are extended from the non-atomic Zermelo–Fraenkel set theory to the world of atomic objects with finite support, while other properties are specific to...

Membrane computing provides computational devices inspired by living cells (called membrane systems) that are proved to be computationally universal. It is a theoretical challenge to find the minimum of resources to get the full power of a Turing machine. The major contribution of this paper is to present such a system with only ONE membrane and wi...

The article deals with interaction in concurrent systems. A calculus able to express specific communication patterns is defined, together with its abstract control structures. A hypergraph model for these structures is presented. The hypergraphs are able to properly express the communication patterns, providing a fully abstract model for the patter...

We define a process calculus to describe multi-agent systems with timeouts for communication and mobility able to handle knowledge. The knowledge of an agent is represented as sets of trees whose nodes carry information; it is used to decide the interactions with other agents. The evolution of the system with exchanges of knowledge between agents i...

In the framework of finitely supported atomic sets, by using the notion of atomic cardinality and the T-finite support principle (a closure property for supports in some higher-order constructions), we present some finiteness properties of the finitely supported binary relations between infinite atomic sets. Of particular interest are finitely supp...

The focus of this paper is the resource evolution in rule-based systems with some specific restrictions imposed; specifically, some resources are bounded between certain lower and upper thresholds. Such a system is proved to be correct with respect to a type system.We define types over hierarchical multiset structures, and consider well-typing with...

We study the notion of memory associated with membranes systems. Such a memory can be used in various ways; in this paper, we focus on two of them. One way is to consider the memory as a device for tracking how objects evolve. In this perspective, the memory is coded into objects which are enriched with suitable information to keep track on how the...

We define tissue P systems with costs assigning execution costs to the synapses that are used to transport the objects between cells. We use the Priced-Timed Maude rewriting engine to provide an implementation of tissue P systems with costs. The implementation allows us to analyze and verify some behavioural aspects of tissue P systems with costs....

Since reversibility is an inherent property of many natural phenomena, it makes sense to investigate reversibility in natural computing. More exactly, to study reversible computation in rule-based systems inspired by living cells. Thus, we consider systems working with rules over multisets of objects which are evolving in a maximal parallel manner....

The reputation of a process is based on its past and present behaviour; it evolves in time depending on several factors including the actions performed, the reputation of its interacting processes and locations where the process resides. We design a calculus of mobile agents in distributed systems able to handle the dynamics of reputation which cha...

The evolution of a reaction system is usually driven by a fixed set of unconstrained rules. In this paper, we present a different approach by imposing some constraints over the rules. Thus, we define restricted reaction systems which are working with mutually exclusive rules, namely rules that are not allowed to be applied together in the same comp...

The theory of finitely supported algebraic structures is a reformulation of Zermelo-Fraenkel set theory in which every set-based construction is finitely supported according to a canonical action of a group of permutations of some basic elements named atoms. In this paper we study the properties of finitely supported sets that contain infinite unif...

The astrocytes are cells which play an essential role in the functioning and interaction of neurons by feeding the respective neurons with calcium ions. Drawing inspiration from this two-way relationship in which the astrocytes influence and are influenced by the neurons by means of calcium ions, in this paper, we define and study spiking neural P...

Mobile membranes represent a model of computation inspired from the biological movement provided by endocytosis and exocytosis in the living cells. This paper presents a survey of the results treating the computational power of the mobile membranes, their efficiency in solving NP-complete problems, and connections with other formal approaches able...

The validity and the non-validity of choice principles in various models of Zermelo-Fraenkel set theory and of Zermelo-Fraenkel set theory with atoms (including the symmetric models and the permutation models) was investigated in the last century. Actually, choice principles are proved to be independent of the set of axioms for Zermelo-Fraenkel and...

We introduce and study lattices in the framework of finitely supported structures. Various properties of lattices are obtained by extending the classical Zermelo-Fraenkel results from the world of non-atomic structures to the world of atomic finitely supported structures. We particularly prove that Tarski fixed point theorem for Zermelo-Fraenkel co...

We present various fundamental examples of invariant lattices and study their properties. We particularly mention the finitely supported subsets of an invariant set, the finitely supported functions from an invariant set to an invariant complete lattice (i.e. the finitely supported L-fuzzy sets with L being an invariant complete lattice), the finit...

PA-sets are defined as classical sets equipped with actions of the group of all bijections of an amorphous set A. They are constructed in the same way as SAsets, except that for defining PA-sets we consider all the bijections of A, not only the finitary ones. Furthermore, in contrast to the invariant sets, PA-sets do not necessarily satisfy the fin...

We present a large collection of properties of the set of atoms, of its (finite or cofinite) powerset and of its (finite) higher-order powerset in the world of finitely supported algebraic structures. Firstly, we prove that atomic sets have many specific FSM properties (that are not translated from ZF). We can structure these specific properties in...

We introduce and study finitely supported partially ordered sets.We study the notion of ‘cardinality’ for a finitely supported set, proving several properties related to this concept. Some properties are naturally extended from the non-atomic Zermelo-Fraenkel framework into the world of atomic structures with finite supports. In this sense, we prov...

We introduce the theory of atomic finitely supported algebraic structures (that are finitely supported sets equipped with finitely supported internal operations or with finitely supported relations), and describe topics related to this theory such as permutation models of Zermelo-Fraenkel set theory with atoms, Fraenkel- Mostowski set theory, the t...

The theory of finitely supported sets allows the study of structures which are very large, but contain enough symmetries such that they can be concisely represented and manipulated. The equivalence of various definitions of infinity is provable in Zermelo-Fraenkel set theory under the consideration of the axiom of choice. Since in the theory of ato...

Our goal is to emphasize a connection between the approach regarding finitely supported structures and Tarski’s definition of logicality requiring invariance under the one-to-one transformations of a universe of discourse onto itself. We also provide a connection with the Erlangen Program of Felix Klein for the classification of various geometries...

We introduce and study Galois connections between finitely supported ordered structures. Particularly, we present properties of finitely supported Galois connections between invariant complete lattices. As an application, we investigate upper and lower approximations of finitely supported sets using the approximation techniques from the theory of r...

We formally describe finitely supported sets as classical Zermelo-Fraenkel sets equipped with canonical permutation actions, satisfying a certain finite support requirement. We provide higher-order constructions of atomic sets starting from some basic atomic sets. We present basic properties of finitely supported sets and of mappings between finite...

The goal of this chapter is to describe properties of elements placed outside the support of a given element. We present a specific quantifier (introduced initially by Gabbay and Pitts) that encodes ‘for all but finitely many’, and show that is placed between \(\forall\) and \(\exists\).

The notion of abstraction appearing in the theory of nominal sets is used in order to model basic concepts in computer science such as renaming, binding and fresh name. We provide a uniform presentation of the existing results involving abstraction, and provide connections with the theory of finitely supported partially ordered sets.

Reversible computation allows computation to proceed not only in the standard, forward direction, but also backward, recovering past states. While reversible computation has attracted interest for its multiple applications, covering areas as different as low-power computing, simulation, robotics and debugging, such applications need to be supported...

In this chapter we give an overview of techniques for the modelling and reasoning about reversibility of systems, including out-of-causal-order reversibility, as it appears in chemical reactions. We consider the autoprotolysis of water reaction, and model it with the Calculus of Covalent Bonding, the Bonding Calculus, and Reversing Petri Nets. This...

In this paper we introduce imprecise probability for session types. More exactly, we use a probabilistic process calculus in which both nondeterministic external choice and probabilistic internal choice are considered. We propose the probabilistic multiparty session types able to codify the structure of the communications by using some imprecise pr...

The goal of this paper is to present a collection of properties of the set of atoms and the set of finite injective tuples of atoms, as well as of the (finite and cofinite) powersets of atoms in the framework of finitely supported structures. Some properties of atoms are obtained by translating classical Zermelo–Fraenkel results into the new framew...

We use a process calculus to describe easily multiagent systems with timeouts for mobility and communication, and with assigned costs for agents actions and for the locations of a distributed network. After presenting an operational semantics and some results regarding this calculus, we provide a translation of the multiagent systems to weighted ti...

This book presents a set theoretical development for the foundations of the theory of atomic and finitely supported structures. It analyzes whether a classical result can be adequately reformulated by replacing a 'non-atomic structure' with an 'atomic, finitely supported structure’. It also presents many specific properties, such as finiteness, car...

We modify the most used evolution strategy in membrane systems (namely that of maximal parallelism) by imposing a synchronization between rules. A synchronization over a set of rules can be applied only if each rule of the set can be applied at least once. For membrane systems working in the accepting mode, this synchronization is powerful enough t...

A prototyping high-level language is used to describe multi-agent systems using timeouts for migration between explicit locations and local communication in a distributed system. We translate such a high-level specification into the real-time Maude rewriting language. We prove that this translation is correct, and provide an operational corresponde...

This paper deals with the probabilistic behaviours of distributed systems described by a process calculus considering both probabilistic internal choices and nondeterministic external choices. For this calculus we define and study a typing system which extends the multiparty session types in order to deal also with probabilistic behaviours. The cal...

The theory of finitely supported algebraic structures represents a reformulation of Zermelo-Fraenkel set theory in which every construction is finitely supported according to the action of a group of permutations of some basic elements named atoms. In this paper we study the properties of finitely supported sets that contain infinite uniformly supp...

The theory of finitely supported algebraic structures represents a reformulation of Zermelo-Fraenkel set theory in which every construction is finitely supported according to the action of a group of permutations of some basic elements named atoms. In this paper we study the properties of finitely supported sets that contain infinite uniformly supp...

We present a collection of fixed point theorems in the framework of finitely supported structures, preserving the validity of several classical Zermelo-Fraenkel fixed point theorems such as Tarski strong theorem, Bourbaki-Witt theorem, Scott theorem and Tarski-Kantorovitch theorem. We also prove several specific fixed point properties in the framew...

This article explores the proof theory necessary for recommending an expressive but decidable first-order system, named MAV1, featuring a De Morgan dual pair of nominal quantifiers. These nominal quantifiers called “new” and “wen” are distinct from the self-dual Gabbay-Pitts and Miller-Tiu nominal quantifiers. The novelty of these nominal quantifie...

In this paper we introduce a membrane system named adaptive P system which is able to adjust dynamically its behaviour depending on resource availability. Such a system is defined as a tree of membranes in which the objects are organized in multisets, and the rules are applied in a maximal parallel manner. We use guards on the right side of the rul...

We present a metric denotational semantics for an experimental concurrent language inspired by the spiking neural P systems. At syntactic level, the language provides constructions for specifying the neurons, synapses and rules with time delays defining a spiking neural P system. The denotational semantics presented in this paper is designed by usi...

The theory of finitely supported algebraic structures is related to Pitts theory of nominal sets (by equipping finitely supported sets with finitely supported internal algebraic laws). It represents a reformulation of Zermelo Fraenkel set theory obtained by requiring every set theoretical construction to be finitely supported according to a certain...

We present the bonding calculus, a calculus in which it is easy to handle covalent bonds between molecules. Our purpose is to use bonding calculus to model the dynamics of the interactions in biochemical systems. We provide an operational semantics by means of a transition system, and use a known software platform to both simulate the chemical reac...

This issue is dedicated to Professor Maciej Koutny for celebrating his 60th birthday, and consists of �five contributions written by his friends and collaborators.

The N-queens puzzle is a topic of several articles written by Mario Pérez-Jiménez and his collaborators. In this paper we present a family of polarizationless P systems with active membranes and 2-cooperation that provides all the possible solutions for this puzzle. The novelty consists in the method allowing a rather important reduction on the num...

We present a denotational semantics for a simple concurrent language based on Milner's CCS extended with multiparty synchronous interactions. We show that our denotational model is weakly abstract with respect to a corresponding operational semantics. The denotational semantics is designed with metric spaces and continuation semantics for concurren...

We investigate the relationship between time Petri nets and various variants of membrane systems. We first show that adding the feature of “time” to Petri nets makes possible the simulation of the maximal parallel mode of rule application from membrane systems without introducing maximal parallelism to the Petri net semantics. Then we define local...

Studying fuzzy attribute-oriented concept lattices has been a challenging issue of Formal Concept Analysis. In [19], the author introduced a fuzzy similarity relation between two collections of L-sets and proved some properties of this similarity type. In this paper, based on a duality technique which allowed us to transfer some properties from ant...

We study the controlled reversibility in reaction systems, a bio-inspired formalism in which the reactions take place only if some inhibitors are not present. Forward reactions are exactly those of the reaction systems, while reverse reactions happen when a special symbol indicates a change in the environment. The reversible reaction systems are tr...

In this paper we present a mathematical model for a class of membrane systems, emphasizing on constructions of the denotational semantics as fixed points over complete metric spaces (to describe the semantics of multiset rewriting) and metric powerdomains (to describe the nondeterministic behaviour). We use the continuation-passing style, a techniq...

The classical theory of fuzzy sets is extended to a recently developed framework named Finitely Supported Mathematics in order to characterize fuzzy sets over infinite universes in a finitary manner by involving the concept of "finite support". We prove some algebraic properties of the new fuzzy sets within Finitely Supported Mathematics (including...

Distributed systems with explicit locations and process mobility are described in terms of the distributed pi-calculus. The systems described in distributed pi-calculus are translated into a rewriting logic which is executable on the Maude software platform. We prove an operational correspondence allowing to verify properly the properties of the di...

We present a simple prototyping language for describing real-time systems including specific features as timeouts, explicit locations, timed migration and timed communication. The parallel execution of a step is provided by multiset labelled transitions. To illustrate its features, we describe a railway control system, and define some behavioural e...

Recently we have considered the possibility of using bio-inspired mobility for solving a weak NP-complete problem (Partition). In this paper we provide a semi-uniform polynomial solution for a strong NP-complete problem (Bin Packing) by means of membrane computing techniques. The solution employs mobile membranes and elementary membrane division.

Factorization by similarity is a mathematical technique used in formal concept analysis with fuzzy attributes for reducing the complexity of different types of fuzzy concept lattices. In this paper we find the structure of the factor lattice of a fuzzy attribute-oriented concept lattice, namely the intervals representing the blocks of this lattice....

In this paper we provide several computability results looking for minimal ingredients needed to obtain Turing completeness of various bio-inspired computation models (membrane systems). We emphasize the relevance of number two in reaching Turing completeness for several membrane systems.

Membrane systems are described by a language in which multisets of objects are encapsulated in hierarchical structures of compartments. The language provides primitives for parallel communication of objects across membranes and a primitive for membrane creation. The behaviour of each membrane is specified by means of multiset rewriting rules. We pr...

Cell biology provides useful ideas to computer scientists in order to construct models which can provide more efficient computations. In this paper we prove that an abstract model of protein-protein interaction derived from membrane computing has the same computational power as a Turing machine by using a rather small number of proteins having at m...

Fraenkel-Mostowski set theory represents a tool for managing infinite structures in terms of finite objects. In this paper we provide a connection between the concept of logical notions invariant under permutations introduced by Tarski and Fraenkel-Mostowski set theory. More precisely, we prove that some particular sets defined by using the axioms...

We introduce and study a prototyping language for real-time distributed systems involving bounded-time migration and communication. The time constraints of this language are expressed as bounded intervals given by real numbers used to model faithfully the uncertainty of the delay in migration and communication of processes placed at explicit locati...

This paper represents a study of reversibility in parallel rewriting systems over multisets. It emphasizes the controlled reversibility for a particular case of parallel rewriting systems given by membrane systems, a formalism inspired by the cell activity. We define reversible membrane systems in which the scenarios based on regular expressions ar...

We present a transformation of membrane systems, possibly with promoter/inhibitor rules, priority relations, and membrane dissolution, into formulas of the chemical calculus such that terminating computations of membranes correspond to terminating reduction sequences of formulas and vice versa. In the end, the same result can be extracted from the...

We introduce and study two topologies in order to provide a topological interpretation of bases in domain theory. The key finding is that, in a continuous domain, bases correspond exactly to dense sets of one of these new topologies. Moreover, we provide a topological interpretation for several properties of the bases, as well as novel characteriza...

In this book the authors present an alternative set theory dealing with a more relaxed notion of infiniteness, called finitely supported mathematics (FSM). It has strong connections to the Fraenkel-Mostowski (FM) permutative model of Zermelo-Fraenkel (ZF) set theory with atoms and to the theory of (generalized) nominal sets.

Finitely Supported Mathematics (FSM) is the mathematics developed in the framework of invariant/finitely supported structures. The aim of this chapter is to translate into FSM several algebraic concepts which were initially described using the Zermelo-Fraenkel axioms of set theory. We focus on multisets, generalized multisets, partially ordered set...

The finite support axiom of Fraenkel-Mostowski set theory is very strong. We study the consequences of replacing this strong axiom with a weaker one. In this chapter we generalize Fraenkel-Mostowski set theory by giving a new set of axioms which defines Extended Fraenkel-Mostowski set theory. In Extended Fraenkel- Mostowski set theory, instead of t...

In this chapter we present the basics of the Fraenkel-Mostowski framework, by studying concepts like invariant set, Fraenkel-Mostowski set, freshness quantifier, support, finiteness, fresh element, and abstraction. We also prove some original results regarding the consistency of various forms of choice in Finitely Supported Mathematics. Another goa...

The aim of this chapter is to present a set of compact transition rules (transition rules without side conditions) for the monadic version of the fusion calculus (update calculus). These transition rules are expressed using the quantifier ∀ and the freshness quantifier. Using some results presented in the second chapter of this book, we are able to...

This paper describes an approach to the behavioural analysis of sessions. The approach is made possible by the calculus of structures — a deep inference proof calculus, generalising the sequent calculus, where inference rules are applied in any context. The approach involves specifications of global and local sessions inspired by the Scribble langu...

We present a theory of abstract interpretations in the framework of invariant sets by translating the notions of lattices and Galois connections into this framework, and presenting their properties in terms of finitely supported objects. We introduce the notions of invariant correctness relation and invariant representation function, emphasize an e...

This paper provides a type theoretic foundation for descriptive types that appear in Linked Data. Linked Data is data published on the Web according to principles and standards supported by the W3C. Such Linked Data is inherently messy: this is due to the fact that instead of being assigned a strict a priori schema, the schema is inferred a posteri...

The first part of the paper is devoted to a polynomial solution of a well-known NP-complete problem (SAT problem) by using an unconventional computation model provided by P systems with active membranes (with neither polarization nor division rules). An important step of this semi-uniform solution is given by polynomial computing devices to build P...

This paper presents the main steps in defining a Finitely Supported Mathematics by using sets with atoms. Such a mathematics generalizes the classical Zermelo-Fraenkel mathematics, and represents an appropriate framework to work with (infinite) structures in terms of finitely supported objects. We focus on the techniques of translating the Zermelo-...

We present an expressive but decidable first-order system (named MAV1) defined by using the calculus of structures, a generalisation of the sequent calculus. In addition to first-order universal and existential quantifiers the system incorporates a pair of nominal quantifiers called `new' and `wen', distinct from the self-dual Gabbay-Pitts and Mill...

The paper presents first the formal semantics of a parallel formalism inspired by biological cells, and then provides a faithful parallel implementation of this computational model using a known distributed computing middleware and taking care of various synchronization issues. Synchronization is achieved using barriers and preconditions; both refe...

The paper deals with the safety of car control systems in which vehicle-to-vehicle interactions are described in a modular and com positional manner. Such a description simplifies a complex verification process, which involves control decisions regarding acceleration, deceleration, lane switching and breaking distance. We focus on the problem of ad...

According to the axioms of the Fraenkel-Mostowski set theory, we define and study the lower and upper approximations of the (infinite) finitely supported subsets of some infinite nominal sets. We first translate the algebraic structures of lattices and the Galois connections into the Fraenkel-Mostowski framework, and then present their properties i...

We define the notion of finitely supported subgroup of a nominal group, and present some algebraic properties of these subgroups. We prove that the family of all finitely supported subgroups of a nominal group forms a nominal complete lattice and a nominal algebraic domain.

## Projects

Project (1)

Creating a new perspective upon the constructive and symbolic practices of European traditional art, for generating possible new directions for creativity on contemporary/postmodern visual art