16834995
An LDA-based Community Structure Discovery Approach for Large-Scale Social Networks
Community discovery has drawn significant research interests among researchers from many disciplines for its increasing application in multiple, disparate areas, including computer science, biology, social science and so on. This paper describes an LDA(latent Dirichlet Allocation)-based hierarchical Bayesian algorithm, namely SSN-LDA (simple social network LDA). In SSN-LDA, communities are modeled as latent variables in the graphical model and defined as distributions over the social actor space. The advantage of SSN-LDA is that it only requires topological information as input. This model is evaluated on two research collaborative networkst: CtteSeer and NanoSCI. The experimental results demonstrate that this approach is promising for discovering community structures in large-scale networks.
17695045
A Multi-Agent Approach for Peer-to-Peer Based Information Retrieval System
This paper develops and analyzes distributed search techniques for use in a peer-to-peer (P2P) network-based Information Retrieval (IR) system. In the absence of a centralized mediator with global knowledge that directs requests to appropriate agents, agents must cooperate to forward the queries among themselves so as to find appropriate agents, and return and merge the results in order to fulfill the information retrieval task in a distributed environment. In our approach, the agent society is connected through an agent-view structure maintained by each agent. Initially, the agent-view structures are formed by agents connecting to each other randomly. However, we show that such an approach can be significantly enhanced by dynamically reorganizing the underlying agent-view topology and deploying contextsensitive distributed search algorithms. Experimental results indicate that appropriate organizational structures and distributed search mechanisms can have a positive influence on system performance.
43897550
Forming and searching content-based hierarchical agent clusters in distributed information retrieval systems
The organization and collaborative protocols of agent societies are becoming increasingly important with the growing size of agent networks. Particularly, in a multi-agent-based content-sharing system, a flat, peer-to-peer P2P agent organization is not the most efficient organization for locating relevant agents for queries. This paper not only develops and analyzes a hierarchical agent group formation protocol to build a hybrid organization for large-scale content sharing systems, but proposes a context-aware distributed search algorithm to take advantage of such an organization as well. During the organization formation process, the agents manage their agent-view structures to form a hierarchical topology in an incremental fashion. The algorithm aims to place those agents with similar content in the same group. We evaluate the system performance based on TREC VLC 921 datasets. The results of the experiment demonstrate a significant increase in the cumulative recall ratio CRR measure compared to the flat agent organization and structure.
18572663
Bernoulli Embedding Model and Its Application in Texture Mapping
A novel texture mapping technique is proposed based on nonlinear dimension reduction, called Bernoulli logistic embedding (BLE). Our probabilistic embedding model builds texture mapping with minimal shearing effects. A log-likelihood function, related to the Bregman distance, is used to measure the similarity between two related matrices defined over the spaces before and after embedding. Low-dimensional embeddings can then be obtained through minimizing this function by a fast block relaxation algorithm. To achieve better quality of texture mapping, the embedded results are adopted as initial values for mapping enhancement by stretch-minimizing. Our method can be applied to both complex mesh surfaces and dense point clouds.
41201857
A Note on the Number of Perfect Matchings of Bipartite Graphs
Abstract Let G be a bipartite graph with 2n vertices, A its adjacency matrix and K the number of perfect matchings. For plane bipartite graphs each interior face of which is surrounded by a circuit of length 4s + 2, s ϵ {1, 2, …}, an elegant formula, i.e. det A = (−1)nK2, had been rigorously proved by Cvetkovic et al. (1982). For general bipartite graphs, this note contains a necessary and sufficient condition for the above relation to hold. A fast algorithm to check if a plane bipartite graph has such a relation is given.
1402660
On Unstructured File Sharing Networks
We study the interaction among users of unstructured file sharing applications, who compete for available network resources (link bandwidth or capacity) by opening multiple connections on multiple paths so as to accelerate data transfer. We model this interaction with an unstructured file sharing game. Users are players and their strategies are the numbers of sessions on available paths. We consider a general bandwidth sharing framework proposed by Kelly [1] and Mo and Walrand [2], with TCP as a special case. Furthermore, we incorporate the Tit-for-Tat strategy (adopted by BitTorrent [3] networks) into the unstructured file sharing game to model the competition in which a connection can be set up only when both users find this connection beneficial. We refer to this as an overlay formation game. We prove the existence of Nash equilibrium in several variants of both games, and quantify the losses of efficiency of Nash equilibria. We find that the loss of efficiency due to selfish behavior is still unbounded even when the Tit-for-Tat strategy is believed to prevent selfish behavior.
5847118
A self-tuning structure for adaptation in TCP/AQM networks
Congestion control in TCP/AQM networks is expected to perform well for a wide-range of conditions, but recent advances in modeling and analysis indicate that present AQM schemes need an extra dose of adaptability to cope. This paper answers the call and proposes a self-tuning structure wherein AQM parameters are automatically tuned in response to on-line estimation of link capacity and traffic load. This approach is applicable to any AQM scheme that is parameterizable in terms of link capacity and TCP load. In this paper, we will describe this self-tuning structure, illustrate its application to PI and RED AQMs, provide stability analysis, and conduct <tt>ns</tt> simulations to compare with both fixed AQM schemes and the recently proposed adaptive RED.
9323396
Inducing Word Alignments with Bilexical Synchronous Trees
This paper compares different bilexical tree-based models for bilingual alignment. EM training for the new model benefits from the dynamic programming "hook trick". The model produces improved dependency structure for both languages.