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149
Computing with Membranes
 JOURNAL OF COMPUTER AND SYSTEM SCIENCES
, 1998
"... We introduce a new computability model, of a distributed parallel type, based on the notion of a membrane structure. Such a structure consists of several celllike membranes, recurrently placed inside a unique "skin" membrane. A plane representation is a Venn diagram without intersected se ..."
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Cited by 355 (4 self)
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We introduce a new computability model, of a distributed parallel type, based on the notion of a membrane structure. Such a structure consists of several celllike membranes, recurrently placed inside a unique "skin" membrane. A plane representation is a Venn diagram without intersected sets and with a unique superset. In the regions delimited by the membranes there are placed objects; the obtained construct is called a supercell. These objects are assumed to evolve: each object can be transformed in other objects, can pas through a membrane, or can disolve the membrane in which it is placed. A priority relation between evolution rules can be considered. The evolution is done in parallel for all objects able to evolve. In this way, we obtain a computing device (we call it a supercell system): start with a certain number of objects in a certain membrane and let the system evolve; if it will halt (no object can further evolve), then the computation is finished, with the result given as...
The monadic secondorder logic of graphs I. Recognizable sets of Finite Graphs
 Information and Computation
, 1990
"... The notion of a recognizable sef offinite graphs is introduced. Every set of finite graphs, that is definable in monadic secondorder logic is recognizable, but not vice versa. The monadic secondorder theory of a contextfree set of graphs is decidable. 0 19W Academic Press. Inc. This paper begins ..."
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Cited by 209 (17 self)
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The notion of a recognizable sef offinite graphs is introduced. Every set of finite graphs, that is definable in monadic secondorder logic is recognizable, but not vice versa. The monadic secondorder theory of a contextfree set of graphs is decidable. 0 19W Academic Press. Inc. This paper begins an investigation of the monadic secondorder logic of graphs and of sets of graphs, using techniques from universal algebra, and the theory of formal languages. (By a graph, we mean a finite directed hyperedgelabelled hypergraph, equipped with a sequence of distinguished vertices.) A survey of this research can be found in Courcelle [ 111. An algebraic structure on the set of graphs (in the above sense) has been proposed by Bauderon and Courcelle [2,7]. The notion of a recognizable set of finite graphs follows, as an instance of the general notion of recognizability introduced by Mezei and Wright in [25]. A graph can also be considered as a logical structure of a certain type. Hence, properties of graphs can be written in firstorder logic or in secondorder logic. It turns out that monadic secondorder logic, where quantifications over sets of vertices and sets of edges are used, is a reasonably powerful logical language (in which many usual graph properties can be written), for which one can obtain decidability results. These decidability results do not hold for secondorder logic, where quantifications over binary relations can also be used. Our main theorem states that every definable set of finite graphs (i.e., every set that is the set of finite graphs satisfying a graph property expressible in monadic secondorder logic) is recognizable. * This work has been supported by the “Programme de Recherches Coordonntes: Mathematiques et Informatique.”
Computing on an Anonymous Ring
 Journal of the ACM
, 1988
"... Abstract. The computational capabilities of a system of n indistinguishable (anonymous) processors arranged on a ring in the synchronous and asynchronous models of distributed computation are analyzed. A precise characterization of the functions that can be computed in this setting is given. It is s ..."
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Cited by 86 (2 self)
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Abstract. The computational capabilities of a system of n indistinguishable (anonymous) processors arranged on a ring in the synchronous and asynchronous models of distributed computation are analyzed. A precise characterization of the functions that can be computed in this setting is given. It is shown that any of these functions can be computed in O(r?) messages in the asynchronous model. This is also proved to be a lower bound for such elementary functions as AND, SUM, and Orientation. In the synchronous model any computable function can be computed in O(n log n) messages. A ring can be oriented and start synchronized within the same bounds. The main contribution of this paper is a new technique for proving lower bounds in the synchronous model. With this technique tight lower bounds of O(nlogn) (for particular n) are proved for XOR, SUM, Orientation, and Start Synchronization. The technique is based on a stringproducing mechanism from formal language theory, first introduced by Thue to study squarefree words. Two methods for generalizing the synchronous lower bounds to arbitrary ring sizes are presented.
An Efficient Compiler for Weighted Rewrite Rules
 IN 34TH ANNUAL MEETING OF THE ASSOCIATION FOR COMPUTATIONAL LINGUISTICS
, 1996
"... Contextdependent rewrite rules are used in many areas of natural language and speech processing. Work in computational phonology has demonstrated that, given certain conditions, such rewrite rules can be represented as finitestate transducers (FSTs). We describe a new algorithm for compilin ..."
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Cited by 75 (25 self)
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Contextdependent rewrite rules are used in many areas of natural language and speech processing. Work in computational phonology has demonstrated that, given certain conditions, such rewrite rules can be represented as finitestate transducers (FSTs). We describe a new algorithm for compiling rewrite rules into FSTs. We show the algorithm to be simpler and more efficient than existing algorithms. Further, many
The Many Facets of Natural Computing
"... related. I am confident that at their interface great discoveries await those who seek them. ” (L.Adleman, [3]) 1. FOREWORD Natural computing is the field of research that investigates models and computational techniques inspired by nature and, dually, attempts to understand the world around us in t ..."
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Cited by 29 (1 self)
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related. I am confident that at their interface great discoveries await those who seek them. ” (L.Adleman, [3]) 1. FOREWORD Natural computing is the field of research that investigates models and computational techniques inspired by nature and, dually, attempts to understand the world around us in terms of information processing. It is a highly interdisciplinary field that connects the natural sciences with computing science, both at the level of information technology and at the level of fundamental research, [98]. As a matter of fact, natural computing areas and topics come in many flavours, including pure theoretical research, algorithms and software applications, as well as biology, chemistry and physics experimental laboratory research. In this review we describe computing paradigms abstracted
LSystems: From The Theory To Visual Models Of Plants
, 1996
"... Recent advances in computer graphics have made it possible to visualize mathematical models of biological structures and processes with unprecedented realism. The resulting images, animations, and interactive systems are useful as research and educational tools in developmental biology and ecolog ..."
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Cited by 28 (1 self)
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Recent advances in computer graphics have made it possible to visualize mathematical models of biological structures and processes with unprecedented realism. The resulting images, animations, and interactive systems are useful as research and educational tools in developmental biology and ecology. Prospective applications also include computerassisted landscape architecture, design of new varieties of plants, and crop yield prediction. In this paper we revisit foundations of the applications of Lsystems to the modeling of plants, and we illustrate them using recently developed sample models.
Grammar Based Codes: A New Class of Universal Lossless Source Codes
 IEEE TRANSACTIONS ON INFORMATION THEORY
, 2000
"... We investigate a type of lossless source code called a grammar based code, which, in response to any input data string x over a fixed finite alphabet, selects a contextfree grammar Gx representing x in the sense that x is the unique string belonging to the language generated by Gx. Lossless compres ..."
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Cited by 18 (2 self)
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We investigate a type of lossless source code called a grammar based code, which, in response to any input data string x over a fixed finite alphabet, selects a contextfree grammar Gx representing x in the sense that x is the unique string belonging to the language generated by Gx. Lossless compression of x takes place indirectly via compression of the production rules of the grammar Gx. It is shown that, subject to some mild restrictions, a grammar based code is a universal code with respect to the family of finite state information sources over the finite alphabet. Redundancy bounds for grammar based codes are established. Reduction rules for designing grammar based codes are presented.