913 research outputs found
L???acto administrativo
No full textManuale di diritto pubblico/amministrativo italiano pubblicato in lingua spagnola.
Il contributo si sofferma sull'atto amministrativo.
Accettazione nel 200
Amortized efficiency of a path retrieval data structure
No full textAbstractA data structure is presented for the problem of maintaining a digraph under an arbitrary sequence of two kinds of operations: an Add operation that inserts an arc in the digraph, and a Searchpath operation that checks the presence of a path between a pair of nodes. Our data structure supports both operations in O(n) amortized time and requires O(n2) space, where n is the number of nodes in the digraph
Graph analytics on modern massively parallel systems
No full textGraphs provide a very flexible abstraction for understanding and modeling complex systems in many fields such as physics, biology, neuroscience, engineering, and social science. Only in the last two decades, with the advent of Big Data era, supercomputers equipped by accelerators –i.e., Graphics Processing Unit (GPUs)–, advanced networking, and highly parallel file systems have been used to analyze graph properties such as reachability, diameter, connected components, centrality, and clustering coefficient. Today graphs of interest may be composed by millions, sometimes billions, of nodes and edges and exhibit a highly irregular structure. As a consequence, the design of efficient and scalable graph algorithms is an extraordinary challenge due to irregular communication and memory access patterns, high synchronization
costs, and lack of data locality. In the present dissertation, we start off with a brief and gentle introduction for the reader to graph analytics and massively parallel systems. In particular, we present the intersection between graph analytics and parallel architectures in the current state-of-the-art and discuss the challenges encountered when solving such problems on large-scale graphs on these architectures (Chapter 1). In Chapter 2, some preliminary definitions and graph-theoretical notions are provided together with a description of the synthetic graphs used in the literature to model real-world networks. In Chapters 3-5, we present and tackle three different relevant problems in graph analysis: reachability (Chapter 3), Betweenness Centrality (Chapter 4), and clustering coefficient (Chapter 5). In detail, Chapter 3 tackles reachability problems by providing two scalable algorithms and implementations which efficiently solve st-connectivity problems on very large-scale graphs Chapter 4 considers the problem of identifying most relevant nodes in a network which plays a crucial role in several applications, including transportation and communication networks, social network analysis, and biological networks. In particular, we focus on a well-known centrality metrics,
namely Betweenness Centrality (BC), and present two different distributed algorithms for the BC computation on unweighted and weighted graphs. For unweighted graphs, we present a new communication-efficient algorithm based on the combination of bi-dimensional (2D) decomposition and multi-level parallelism. Furthermore, new algorithms which exploit the underlying graph topology to reduce the time and space usage of betweenness centrality computations are described as well. Concerning weighted graphs, we provide a scalable algorithm based on an algebraic formulation of the problem. Finally, thorough comprehensive experimental results on synthetic and real-
world large-scale graphs, we show that the proposed techniques are effective in practice and achieve significant speedups against state-of-the-art solutions. Chapter 5 considers clustering coefficients problem. Similarly to Betweenness Centrality, it is a fundamental tool in network analysis, as it specifically measures how nodes tend to cluster together in a network. In the chapter, we first extend caching techniques to Remote Memory Access (RMA) operations on distributed-memory system. The caching layer is mainly designed to avoid inter-node communications in order to achieve similar benefits for irregular applications as communication-avoiding algorithms. We also show how cached RMA is able to improve the performance of a new distributed asynchronous algorithm for the computation of local clustering coefficients. Finally, Chapter 6 contains a brief summary of the key contributions described in the dissertation and presents potential future directions of the
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L'acto administrativo
No full textManuale di diritto pubblico/amministrativo italiano pubblicato in lingua spagnola.
Il contributo si sofferma sull'atto amministrativo.
Accettazione nel 200
Fully dynamic all pairs shortest paths with real edge weights
No full textWe present the first fully dynamic algorithm for maintaining all pairs shortest paths in directed graphs with real-valued edge weights. Given a dynamic directed graph G such that each edge can assume at most S different real values, we show how to support updates deterministically in O(S · n2.5 log3 n) amortized time and queries in optimal worst-case time. No previous fully dynamic algorithm was known for this problem. In the special case where edge weights can only be increased, we give a randomized algorithm with one-sided error which supports updates faster in O (S · n log3 n) amortized time
Algoritmi e strutture dati (seconda edizione)
No full textQuesto libro offre un'introduzione allo studio degli algoritmi e delle strutture dati, cercando di conciliare comprensibilità, chiarezza di esposizione e rigore matematico. Particolare enfasi è posta sull'astrazione delle tecniche e delle metodologie generali di progetto e analisi di algoritmi, stimolandone la comprensione intuitiva dei principi fondamentali. Il libro è concepito soprattutto per corsi universitari delle facoltà di ingegneria e di scienze matematiche, fisiche e naturali. Il testo, pur essendo indipendente dalla scelta di un particolare linguaggio di programmazione, adotta un approccio orientato agli oggetti sia nella descrizione delle strutture dati che nello pseudocodice utilizzato per descrivere gli algoritmi. In tal modo, pur astraendo dai dettagli implementativi di basso livello, gli algoritmi presentati non risultano troppo distanti da una loro reale implementazione
Mathematical foundations of computer science 2015 : 40th International Symposium, MFCS 2015, Milan, Italy, August 24-28, 2015; proceedings. 1
No full text
Book review: Schuppert, G.F. 2010, Staat als Prozess. Eine staatstheoretische Skizze in sieben Aufzügen
No full textG.F. Schuppert contends the state is the central point of reference in social and political science as well as in legal and economic studies. In devoting the central issue of this book to the state, the author makes it not only a work of central interest for the mentioned disciplines but also opens up the subject for a broad audience
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