Results 1 
6 of
6
Exact and approximate algorithms for computing the hyperbolicity of largescale graphs
, 2012
"... ..."
Treelike structure in large social and information networks
, 2013
"... Although large social and information networks are often thought of as having hierarchical or treelike structure, this assumption is rarely tested. We have performed a detailed empirical analysis of the treelike properties of realistic informatics graphs using two very different notions of treel ..."
Abstract

Cited by 6 (2 self)
 Add to MetaCart
Although large social and information networks are often thought of as having hierarchical or treelike structure, this assumption is rarely tested. We have performed a detailed empirical analysis of the treelike properties of realistic informatics graphs using two very different notions of treelikeness: Gromov’s δhyperbolicity, which is a notion from geometric group theory that measures how treelike a graph is in terms of its metric structure; and tree decompositions, tools from structural graph theory which measure how treelike a graph is in terms of its cut structure. Although realistic informatics graphs often do not have meaningful treelike structure when viewed with respect to the simplest and most popular metrics, e.g., the value of δ or the treewidth, we conclude that many such graphs do have meaningful treelike structure when viewed with respect to more refined metrics, e.g., a sizeresolved notion of δ or a closer analysis of the tree decompositions. We also show that, although these two rigorous notions of treelikeness capture very different treelike structures in worstcase, for realistic informatics graphs they empirically identify surprisingly similar structure. We interpret this treelike structure in terms of the recentlycharacterized “nested coreperiphery” property of large informatics graphs; and we show that the fast and scalable kcore heuristic can be used to identify this treelike structure.
Abstract
, 1999
"... We evaluate a class of learning algorithms known as inductive logic programming (ILP) methods on the task of predicting fault occurrence in C++ classes. Using these methods, a large space of possible hypotheses is searched in an automated fashion; further, the hypotheses are based directly on an abs ..."
Abstract

Cited by 1 (0 self)
 Add to MetaCart
(Show Context)
We evaluate a class of learning algorithms known as inductive logic programming (ILP) methods on the task of predicting fault occurrence in C++ classes. Using these methods, a large space of possible hypotheses is searched in an automated fashion; further, the hypotheses are based directly on an abstract logical representation of the software, rather than on manually proposed numerical metrics that predict fault density. We compare two ILP systems, FOIL and FLIPPER, and conclude that FLIPPER generally outperforms FOIL on this problem. We analyze the reasons for the differing performance of these two systems, and based on the analysis, propose two extensions to FLIPPER: a userdirected bias towards easytoevaluate clauses, and an extension that allows FLIPPER to learn “counting clauses”. Counting clauses augment logic programs with a variation of the “number restrictions ” used in description logics, and significantly improve performance on this problem when prior knowledge is used. We also evaluate the use of ILP techniques for automatic generation of boolean indicators and numeric metrics from the calling tree representation. 0 1
Evaluating OpenMP Tasking at Scale for the Computation of Graph Hyperbolicity
"... Abstract. We describe using OpenMP to compute δhyperbolicity, a quantity of interest in social and information network analysis, at a scale that uses up to 1000 threads. By considering both OpenMP workshare and tasking models to parallelize the computations, we find that multiple task levels permit ..."
Abstract

Cited by 1 (1 self)
 Add to MetaCart
Abstract. We describe using OpenMP to compute δhyperbolicity, a quantity of interest in social and information network analysis, at a scale that uses up to 1000 threads. By considering both OpenMP workshare and tasking models to parallelize the computations, we find that multiple task levels permits finer grained tasks at runtime and results in better performance at scale than worksharing constructs. We also characterize effects of task inflation, load balancing, and scheduling overhead in this application, using both GNU and Intel compilers. Finally, we show how OpenMP 3.1 tasking clauses can be used to mitigate overheads at scale. 1
A Game Theoretic Model for the Formation of Navigable SmallWorld Networks
"... Kleinberg proposed a family of smallworld networks to explain the navigability of largescale realworld social networks. However, the underlying mechanism that drives real networks to be navigable is not yet well understood. In this paper, we present a game theoretic model for the formation of ..."
Abstract
 Add to MetaCart
(Show Context)
Kleinberg proposed a family of smallworld networks to explain the navigability of largescale realworld social networks. However, the underlying mechanism that drives real networks to be navigable is not yet well understood. In this paper, we present a game theoretic model for the formation of navigable small world networks. We model the network formation as a game in which people seek for both high reciprocity and longdistance relationships. We show that the navigable smallworld network is a Nash Equilibrium of the game. Moreover, we prove that the navigable smallworld equilibrium tolerates collusions of any size and arbitrary deviations of a large random set of nodes, while nonnavigable equilibria do not tolerate small group collusions or random perturbations. Our empirical evaluation further demonstrates that the system always converges to the navigable network even when limited or no information about other players ’ strategies is available. Our theoretical and empirical analyses provide important new insight on the connection between distance, reciprocity and navigability in social networks.