We develop a framework for algorithms finding the diameter in graphs of bounded distance Vapnik-Chervonenkis dimension, in (parameterized) subquadratic time complexity. The class of bounded distance VC-dimension graph...
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SimRank is a popular measure for evaluating node similarities in graphs, but its high computational cost limits scalability for large graphs. The ExactSim [1] algorithm achieves precise single-source SimRank similarit...
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In node classification tasks, traditional methods like LPA-GCN struggle with scalability and sensitivity to label noise. We propose LPA-graphSAGE, combining the Label Propagation Algorithm with graphSAGE’s ...
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We consider the problem of vertex recoloring: we are given n vertices with their initial coloring, and edges arrive in an online fashion. The algorithm is required to maintain a valid coloring by means of vertex recol...
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ISBN:
(纸本)9783959773652
We consider the problem of vertex recoloring: we are given n vertices with their initial coloring, and edges arrive in an online fashion. The algorithm is required to maintain a valid coloring by means of vertex recoloring, where recoloring a vertex incurs a cost. The problem abstracts a scenario of job placement in machines (possibly in the cloud), where vertices represent jobs, colors represent machines, and edges represent "anti affinity" (disengagement) constraints. Online coloring in this setting is a hard problem, and only a few cases were analyzed. One family of instances which is fairly well-understood is bipartite graphs, i.e., instances in which two colors are sufficient to satisfy all constraints. In this case it is known that the competitive ratio of vertex recoloring is Θ(log n). In this paper we propose a generalization of the problem, which allows using additional colors (possibly at a higher cost), to improve overall performance. Concretely, we analyze the simple case of bipartite graphs of bounded largest bond (a bond of a connected graph is an edge-cut that partitions the graph into two connected components). From the upper bound perspective, we propose two algorithms. One algorithm exhibits a trade-off for the uniform-cost case: given Ω(log β) ≤ c ≤ O(log n) colors, the algorithm guarantees that its cost is at most O(logcn ) times the optimal offline cost for two colors, where n is the number of vertices and β is the size of the largest bond of the graph. The other algorithm is designed for the case where the additional colors come at a higher cost, D > 1: given ∆ additional colors, where ∆ is the maximum degree in the graph, the algorithm guarantees a competitive ratio of O(log D). From the lower bounds viewpoint, we show that if the cost of the extra colors is D > 1, no algorithm (even randomized) can achieve a competitive ratio of o(log D). We also show that in the case of general bipartite graphs (i.e., of unbounded bond size), any determinist
While graphs and abstract data structures can be large and complex, practical instances are often regular or highly structured. If the instance has sufficient structure, we might hope to compress the object into a mor...
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We consider an unsplittable version of the minimum max-load multicommodity flow problem, where each demand must be routed along a single path. The objective is to minimize the maximum load on any edge in the network. ...
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A set S⊆V(G) is said to be a hop dominating set if every vertex u∈V(G)\S, there exists a vertex v∈S such that d(u,v)=2 where d(u, v) represents the distance between u and v in G. The minimum k for which there e...
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When transmitting information over a network via communication devices, the parameters of data transmission efficiency and reliability are of paramount importance. Based on the fact that the operator does not have the...
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Identifying Community structures is a fundamental problem in graph analysis. To detect communities in massive contemporary graphs, researchers have extensively explored shared- and distributed-memory parallel algorith...
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ISBN:
(纸本)9798350363074;9798350363081
Identifying Community structures is a fundamental problem in graph analysis. To detect communities in massive contemporary graphs, researchers have extensively explored shared- and distributed-memory parallel algorithms for several methods including Louvain Modularity Optimization and Label Propagation. The widely used Infomap algorithm based on Map Equation Framework (MEF) is known to provide better quality results than other approaches. However, research on parallel community detection using MEF or Infomap is extremely sparse when compared to other methods. We present a comprehensive characterization of Infomap and some of its known parallel implementations to facilitate research into parallel algorithms based on MEF. Most implementations take simple parallelization approaches, leaving strategies used to parallelize similar algorithms such as Louvain untouched. We highlight the scalability limitations of current implementations and implement and evaluate optimizations for MEF based parallel community detection that achieved up to 119% improvement on the overall speedup across the tested datasets.
We study the problem of identifying the source of a stochastic diffusion process spreading on a graph based on the arrival times of the diffusion at a few queried nodes. In a graph G = (V, E), an unknown source node v...
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We study the problem of identifying the source of a stochastic diffusion process spreading on a graph based on the arrival times of the diffusion at a few queried nodes. In a graph G = (V, E), an unknown source node v* is an element of V is drawn uniformly at random, and unknown edge weights w(e) for e is an element of E, representing the propagation delays along the edges, are drawn independently from a Gaussian distribution of mean 1 and variance sigma(2). An algorithm then attempts to identify v* by querying nodes q is an element of V and being told the length of the shortest path between q and v* in graph G weighted by w. We consider two settings: non-adaptive, in which all query nodes must be decided in advance, and adaptive, in which each query can depend on the results of the previous ones. Both settings are motivated by an application of the problem to epidemic processes (where the source is called patient zero), which we discuss in detail. We characterize the query complexity when G is an n-node path. In the non-adaptive setting, Theta(n alpha(2)) queries are needed for sigma(2) <= 1, and Theta(n) for sigma(2) >= 1. In the adaptive setting, somewhat surprisingly, only Theta(log log(1/sigma) n) are needed when sigma(2) <= 1/2, and O(log log n) + O-sigma(1) when sigma(2) >= 1/2. This is the first mathematical study of source identification with time queries in a non-deterministic diffusion process. (c) 2022 The Author(s). Published by Elsevier B.V.
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