... Rossella Petreschi and Andrea Sterbini Department of Computer Science, University "La Sapienza', Via Salaria 113 - 00198 Rome, Italy, e-mail {petreschi,andrea} ~dsi.uniromal.it ... 13. Ricart G. and Agrawala AK An... more
... Rossella Petreschi and Andrea Sterbini Department of Computer Science, University "La Sapienza', Via Salaria 113 - 00198 Rome, Italy, e-mail {petreschi,andrea} ~dsi.uniromal.it ... 13. Ricart G. and Agrawala AK An optimal algorithm for mutual exclusion in computer networks. ...
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Page 1. Rossella Petreschi Giuseppe Persiano Riccardo Silvestri (Eds.) CO Algorithms and Complexity 5th Italian Conference, CIAC 2003 Rome, Italy, May 2003 Proceedings Page 2. Page 3. ... However, all the editions of CIAC have been held... more
Page 1. Rossella Petreschi Giuseppe Persiano Riccardo Silvestri (Eds.) CO Algorithms and Complexity 5th Italian Conference, CIAC 2003 Rome, Italy, May 2003 Proceedings Page 2. Page 3. ... However, all the editions of CIAC have been held in Rome. ...
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A system of asynchronous parallel processes is represented by an exclusion graph in which a vertex is a process and an edge is a pair of mutually excluding processes. The mutual exclusion problem can be managed by simple entrance and exit... more
A system of asynchronous parallel processes is represented by an exclusion graph in which a vertex is a process and an edge is a pair of mutually excluding processes. The mutual exclusion problem can be managed by simple entrance and exit protocols using PVchunk operations on a single shared variable when the graph is a threshold one. Ordman wonders if an efficient way exists for managing mutual exclusion situations modeled by more complex graphs than the threshold ones. A start is made on that here: we present a solution of the problem when the model is in the class of matrogenic graphs, which properly contains the threshold graphs.
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ABSTRACT Let G be a graph whose vertices are contaminated. Assigning a searcher to a contaminated vertex makes it to become guaraded. Removing the searcher of a guarded vertex turns it clear. However, a clear vertex becomes again... more
ABSTRACT Let G be a graph whose vertices are contaminated. Assigning a searcher to a contaminated vertex makes it to become guaraded. Removing the searcher of a guarded vertex turns it clear. However, a clear vertex becomes again contaminated if it has a contaminated neighbour. The node-search number of G is the least number of searchers needed to clear all its vertices. J. Gustedt [Discrete Appl. Math. 45, No. 3, 233-248 (1993; Zbl 0798.68134)] has shown that the problem of determining the node-search number of G is NP-hard for uniform k-starlike graphs. These graphs are generalizations of split graphs, when each vertex of the independent set of its bipartition is replaced by a clique formed by k vertices of identical neighbourhood. We describe necessary and sufficient conditions for finding the node-search number of a uniform k-starlike graph. The characterization described extends a corresponding result for split graphs by T. Kloks [Treewidth. Computations and approximations. Lecture Notes in Computer Science. 842 (Springer-Verlag, Berlin) (1994; Zbl 0825.68144)]. In addition, it leads to a new algorithm for finding the node-search number for graphs of this class.
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Research Interests: Data Structure and Cocoon
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ABSTRACT
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In this paper we present a new software visualization tool, called LEONARDO, which allows to visualize algorithms on graphs (but is easily extendable to other kinds of data structures). LEONARDO's main peculiarities are a complete... more
In this paper we present a new software visualization tool, called LEONARDO, which allows to visualize algorithms on graphs (but is easily extendable to other kinds of data structures). LEONARDO's main peculiarities are a complete use of the undo/redo mode, bounded only by the potentiality of the working machine, and a mapping between concrete and abstract data structures allowed by a new logic visualization language.
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Abstract This paper is concerned with the maximum cut problem in parallel on cubic graphs. New theoretical results characterizing the cardinality of the cut are presented. These results make it possible to design a simple combinatorial O... more
Abstract This paper is concerned with the maximum cut problem in parallel on cubic graphs. New theoretical results characterizing the cardinality of the cut are presented. These results make it possible to design a simple combinatorial O (log n) time parallel algorithm, running on a CRCW P-RAM with O (n) processors. The approximation ratio achieved by the algorithm is 1· 3 and improves the best known parallel approximation ratio, ie 2, in the special class of cubic graphs. The algorithm also guarantees that the size of the returned ...
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ABSTRACT To examine, analyze, and manipulate a problem to the point of designing an algorithm for solving it is an exercise of fundamental value in many fields. With so many everyday activities governed by algorithmic principles, the... more
ABSTRACT To examine, analyze, and manipulate a problem to the point of designing an algorithm for solving it is an exercise of fundamental value in many fields. With so many everyday activities governed by algorithmic principles, the power, precision, reliability and speed of execution demanded by users have transformed the design and construction of algorithms from a creative, artisanal activity into a full-fledged science in its own right. This book is aimed at all those who exploit the results of this new science, as designers and as consumers. The first chapter is an overview of the related history, demonstrating the long development of ideas such as recursion and more recent formalizations such as computability. The second chapter shows how the design of algorithms requires appropriate techniques and sophisticated organization of data. In the subsequent chapters the contributing authors present examples from diverse areas - such as routing and networking problems, Web search, information security, auctions and games, complexity and randomness, and the life sciences - that show how algorithmic thinking offers practical solutions and also deepens domain knowledge. The contributing authors are top-class researchers with considerable academic and industrial experience; they are also excellent educators and communicators and they draw on this experience with enthusiasm and humor. This book is an excellent introduction to an intriguing domain and it will be enjoyed by undergraduate and postgraduate students in computer science, engineering, and mathematics, and more broadly by all those engaged with algorithmic thinking.
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Page 1. Computer Science 767 Giancarlo Bongiovanni Giorgio Gambosi Rossella Petreschi (Eds.) Algorithms and Complexity 4th Italian Conference, CIAC 2000 Rome, Italy, March 2000 Proceedings Springer Page 2. Page 3. ...
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In this paper we prove a conjecture left open by Bodlaender et al. [3] concerning L(2, 1)-labeling of outerplanar graphs. L(2, 1)-labeling is a coloring problem arising from frequency assignment in multihop radio networks, in which... more
In this paper we prove a conjecture left open by Bodlaender et al. [3] concerning L(2, 1)-labeling of outerplanar graphs. L(2, 1)-labeling is a coloring problem arising from frequency assignment in multihop radio networks, in which adjacent nodes must receive colors that are at least two apart while nodes at distance two must receive different colors. Namely, we improve the
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Research Interests: Escape and Linear Time
... orthogonal drawing with the minimum number of bends Time Gridsize Total [lum-ber ot bends i O(n4m log n not investigated mini-orthogonal O(n) ~lanar ammortized drawing it G is pla-nax, noth-ing if G is not planar ~rthogonal O(n)... more
... orthogonal drawing with the minimum number of bends Time Gridsize Total [lum-ber ot bends i O(n4m log n not investigated mini-orthogonal O(n) ~lanar ammortized drawing it G is pla-nax, noth-ing if G is not planar ~rthogonal O(n) ,drawing I(pla-nar if G is planar) mum ...
This paper investigates a variant of the general problem of assigning channels to the stations of a wireless network when the graph representing the possible interferences is a matrogenic graph. In this problem, channels assigned to... more
This paper investigates a variant of the general problem of assigning channels to the stations of a wireless network when the graph representing the possible interferences is a matrogenic graph. In this problem, channels assigned to adjacent vertices must be at least two apart, while the same channel can be reused for vertices whose distance is at least three. Linear
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ABSTRACT We consider the task of learning a ring in a distributed way: each node of an unknown ring has to construct a labeled map of it. Nodes are equipped with unique labels. Communication proceeds in synchronous rounds. In every round... more
ABSTRACT We consider the task of learning a ring in a distributed way: each node of an unknown ring has to construct a labeled map of it. Nodes are equipped with unique labels. Communication proceeds in synchronous rounds. In every round every node can send arbitrary messages to its neighbors and perform arbitrary local computations. We study tradeoffs between the time (number of rounds) and the cost (number of messages) of completing this task in a deterministic way: for a given time T we seek bounds on the smallest number of messages needed for learning the ring in time T. Our bounds depend on the diameter D of the ring and on the delayθ=T−D above the least possible time D in which this task can be performed. We prove a lower bound Ω(D2/θ) on the number of messages used by any algorithm with delay θ, and we design a class of algorithms that give an almost matching upper bound: for any positive constant 0<ε<1 there is an algorithm working with delay θ≤D and using O(D2 (log*D)/θ1−ε) messages.