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32
Structural Cohesion and Embeddedness: A hierarchical conception of social groups.
 American Sociological Review
, 2000
"... While questions about social cohesion lie at the core of our discipline, definitions are often vague and difficult to operationalize. We link research on social cohesion and social embeddedness by developing a conception of structural cohesion based on network nodeconnectivity. Structural cohesion i ..."
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Cited by 128 (14 self)
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While questions about social cohesion lie at the core of our discipline, definitions are often vague and difficult to operationalize. We link research on social cohesion and social embeddedness by developing a conception of structural cohesion based on network nodeconnectivity. Structural cohesion is defined as the minimum number of actors who, if removed from a group, would disconnect the group. A structural dimension of embeddedness can then be defined through the hierarchical nesting of these cohesive structures. We demonstrate the empirical applicability of our conception of nestedness in two dramatically different substantive settings and discuss additional theoretical implications with reference to a wide array of substantive fields. "...social solidarity is a wholly moral phenomenon which by itself is not amenable to exact observation and especially not to measurement." (Durkheim, (1893 [1984], p.24) "The social structure [of the dyad] rests immediately on the one and on the other of the two, and the secession of either would destroy the whole. ... As soon, however, as there is a sociation of three, a group continues to exist even in case one of the members drops out." (Simmel (1908 [1950], p. 123)
Social Cohesion and Embeddedness: A hierarchical conception of social groups
, 2002
"... While questions about social cohesion lie at the core of our discipline, no clear definition of cohesion exists. We present a definition of social cohesion based on network connectivity that leads to an operationalization of social embeddedness. We define cohesiveness as the minimum number of actors ..."
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Cited by 55 (22 self)
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While questions about social cohesion lie at the core of our discipline, no clear definition of cohesion exists. We present a definition of social cohesion based on network connectivity that leads to an operationalization of social embeddedness. We define cohesiveness as the minimum number of actors who, if removed from a group, would disconnect the group. This definition generates hierarchically nested groups, where highly cohesive groups are embedded within less cohesive groups. We discuss the theoretical implications of this definition and demonstrate the empirical applicability of our conception of nestedness by testing the predicted correlates of our cohesion measure within high school friendship and interlocking directorate networks. Keywords: Social networks, social theory, social cohesion, connectivity algorithm, embeddedness. "...social solidarity is a wholly moral phenomenon which by itself is not amenable to exact observation and especially not to measurement." (Durkheim, (1893 [1984], p.24) "The social structure [of the dyad] rests immediately on the one and on the other of the two, and the secession of either would destroy the whole. ... As soon, however, as there is a sociation of three, a group continues to exist even in case one of the members drops out." (Simmel (1908 [1950], p. 123)
Optimal upward planarity testing of singlesource digraphs
 SIAM Journal on Computing
, 1998
"... Abstract. A digraph is upward planar if it has a planar drawing such that all the edges are monotone with respect to the vertical direction. Testing upward planarity and constructing upward planar drawings is important for displaying hierarchical network structures, which frequently arise in softwar ..."
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Cited by 39 (4 self)
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Abstract. A digraph is upward planar if it has a planar drawing such that all the edges are monotone with respect to the vertical direction. Testing upward planarity and constructing upward planar drawings is important for displaying hierarchical network structures, which frequently arise in software engineering, project management, and visual languages. In this paper we investigate upward planarity testing of singlesource digraphs; we provide a new combinatorial characterization of upward planarity and give an optimal algorithm for upward planarity testing. Our algorithm tests whether a singlesource digraph with n vertices is upward planar in O(n) sequential time, and in O(log n) time on a CRCW PRAM with n log log n / log n processors, using O(n) space. The algorithm also constructs an upward planar drawing if the test is successful. The previously known best result is an O(n2)time algorithm by Hutton and Lubiw [Proc. 2nd ACM–SIAM Symposium on Discrete Algorithms, SIAM, Philadelphia, 1991, pp. 203–211]. No efficient parallel algorithms for upward planarity testing were previously known.
Parallel Tree Contraction Part 2: Further Applications
 SIAM JOURNAL ON COMPUTING
, 1991
"... This paper applies the parallel tree contraction techniques developed in Miller and paper [Randomness and Computation, 5, S. Micali, ed., JAI Press, 1989, pp. 4772] to a number of fundamental graph problems. The paper presents an time and processor, a 0sided randomized algorithm for testing the i ..."
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Cited by 34 (3 self)
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This paper applies the parallel tree contraction techniques developed in Miller and paper [Randomness and Computation, 5, S. Micali, ed., JAI Press, 1989, pp. 4772] to a number of fundamental graph problems. The paper presents an time and processor, a 0sided randomized algorithm for testing the isomorphism of trees, and an n) time, nprocessor algorithm for maximal isomorphism and for common subexpression elimination. An time, nprocessor algorithm for computing the canonical forms of trees and subtrees is given. An Ologn time algorithm for computing the tree of 3connected components of a graph, an n)time algorithm for computing an explicit planar embedding of a planar graph, and an n)time algorithm for computing a canonical form for a planar graph are also given. All these latter algorithms use only processors on a Parallel Random Access Machine (PRAM) model with concurrent writes and concurrent reads.
Planarity Testing in Parallel
, 1994
"... We present a parallel algorithm based on open ear decomposition to construct an embedding of a graph onto the plane or report that the graph is nonplanar. Our parallel algorithm runs on a CRCW PRAM in logarithmic time with a number of processors bounded by that needed for finding connected component ..."
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Cited by 33 (6 self)
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We present a parallel algorithm based on open ear decomposition to construct an embedding of a graph onto the plane or report that the graph is nonplanar. Our parallel algorithm runs on a CRCW PRAM in logarithmic time with a number of processors bounded by that needed for finding connected components in a graph and for performing bucket sort.
Parallel Open Ear Decomposition with Applications to Graph Biconnectivity and Triconnectivity
 Synthesis of Parallel Algorithms
, 1992
"... This report deals with a parallel algorithmic technique that has proved to be very useful in the design of efficient parallel algorithms for several problems on undirected graphs. We describe this method for searching undirected graphs, called "open ear decomposition", and we relate thi ..."
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Cited by 26 (9 self)
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This report deals with a parallel algorithmic technique that has proved to be very useful in the design of efficient parallel algorithms for several problems on undirected graphs. We describe this method for searching undirected graphs, called "open ear decomposition", and we relate this decomposition to graph biconnectivity. We present an efficient parallel algorithm for finding this decomposition and we relate it to a sequential algorithm based on depthfirst search. We then apply open ear decomposition to obtain an efficient parallel algorithm for testing graph triconnectivity and for finding the triconnnected components of a graph.
Parallel Implementation of Algorithms for Finding Connected Components in Graphs
, 1997
"... In this paper, we describe our implementation of several parallel graph algorithms for finding connected components. Our implementation, with virtual processing, is on a 16,384processor MasPar MP1 using the language MPL. We present extensive test data on our code. In our previous projects [21, 22, ..."
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Cited by 24 (1 self)
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In this paper, we describe our implementation of several parallel graph algorithms for finding connected components. Our implementation, with virtual processing, is on a 16,384processor MasPar MP1 using the language MPL. We present extensive test data on our code. In our previous projects [21, 22, 23], we reported the implementation of an extensible parallel graph algorithms library. We developed general implementation and finetuning techniques without expending too much effort on optimizing each individual routine. We also handled the issue of implementing virtual processing. In this paper, we describe several algorithms and finetuning techniques that we developed for the problem of finding connected components in parallel; many of the finetuning techniques are of general interest, and should be applicable to code for other problems. We present data on the execution time and memory usage of our various implementations.
M.: The Triconnected Abstraction of Process Models
, 2009
"... Abstract. Companies use business process models to represent their working procedures in order to deploy services to markets, to analyze them, and to improve upon them. Competitive markets necessitate complex procedures, which lead to large process specifications with sophisticated structures. Real ..."
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Cited by 17 (9 self)
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Abstract. Companies use business process models to represent their working procedures in order to deploy services to markets, to analyze them, and to improve upon them. Competitive markets necessitate complex procedures, which lead to large process specifications with sophisticated structures. Real world process models can often incorporate hundreds of modeling constructs. While a large degree of detail complicates the comprehension of the processes, it is essential to many analysis tasks. This paper presents a technique to abstract, i.e., to simplify process models. Given a detailed model, we introduce abstraction rules which generalize process fragments in order to bring the model to a higher abstraction level. The approach is suited for the abstraction of large process specifications in order to aid model comprehension as well as decomposing problems of process model analysis. The work is based on process structure trees that have recently been introduced to the field of business process management. 1
OnLine Maintenance of Triconnected Components with SPQRTrees
, 1996
"... We consider the problem of maintaining online the triconnected components of a graph G. Let n be the current number of vertices of G. We present an O(n)space data structure that supports insertions of vertices and edges, and queries of the type “Are there three vertexdisjoint paths between vert ..."
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Cited by 14 (2 self)
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We consider the problem of maintaining online the triconnected components of a graph G. Let n be the current number of vertices of G. We present an O(n)space data structure that supports insertions of vertices and edges, and queries of the type “Are there three vertexdisjoint paths between vertices v1 and v2?” A sequence of k operations takes time O(k · α(k, n)) if G is biconnected (α(k, n) denotes the wellknown Ackermann’s function inverse), and time O(n log n + k) if G is not biconnected. Note that the bounds do not depend on the number of edges of G. We use the SPQRtree, a versatile data structure that represents the decomposition of a biconnected graph with respect to its triconnected components, and the BCtree, which represents the decomposition of a connected graph with respect to its biconnected components.