2,045 research outputs found
Outward Influence and Cascade Size Estimation in Billion-scale Networks
Estimating cascade size and nodes' influence is a fundamental task in social,
technological, and biological networks. Yet this task is extremely challenging
due to the sheer size and the structural heterogeneity of networks. We
investigate a new influence measure, termed outward influence (OI), defined as
the (expected) number of nodes that a subset of nodes will activate,
excluding the nodes in S. Thus, OI equals, the de facto standard measure,
influence spread of S minus |S|. OI is not only more informative for nodes with
small influence, but also, critical in designing new effective sampling and
statistical estimation methods.
Based on OI, we propose SIEA/SOIEA, novel methods to estimate influence
spread/outward influence at scale and with rigorous theoretical guarantees. The
proposed methods are built on two novel components 1) IICP an important
sampling method for outward influence, and 2) RSA, a robust mean estimation
method that minimize the number of samples through analyzing variance and range
of random variables. Compared to the state-of-the art for influence estimation,
SIEA is times faster in theory and up to several orders of
magnitude faster in practice. For the first time, influence of nodes in the
networks of billions of edges can be estimated with high accuracy within a few
minutes. Our comprehensive experiments on real-world networks also give
evidence against the popular practice of using a fixed number, e.g. 10K or 20K,
of samples to compute the "ground truth" for influence spread.Comment: 16 pages, SIGMETRICS 201
Importance Sketching of Influence Dynamics in Billion-scale Networks
The blooming availability of traces for social, biological, and communication
networks opens up unprecedented opportunities in analyzing diffusion processes
in networks. However, the sheer sizes of the nowadays networks raise serious
challenges in computational efficiency and scalability.
In this paper, we propose a new hyper-graph sketching framework for inflence
dynamics in networks. The central of our sketching framework, called SKIS, is
an efficient importance sampling algorithm that returns only non-singular
reverse cascades in the network. Comparing to previously developed sketches
like RIS and SKIM, our sketch significantly enhances estimation quality while
substantially reducing processing time and memory-footprint. Further, we
present general strategies of using SKIS to enhance existing algorithms for
influence estimation and influence maximization which are motivated by
practical applications like viral marketing. Using SKIS, we design high-quality
influence oracle for seed sets with average estimation error up to 10x times
smaller than those using RIS and 6x times smaller than SKIM. In addition, our
influence maximization using SKIS substantially improves the quality of
solutions for greedy algorithms. It achieves up to 10x times speed-up and 4x
memory reduction for the fastest RIS-based DSSA algorithm, while maintaining
the same theoretical guarantees.Comment: 12 pages, to appear in ICDM 2017 as a regular pape
Big Networks: Analysis and Optimal Control
The study of networks has seen a tremendous breed of researches due to the explosive spectrum of practical problems that involve networks as the access point. Those problems widely range from detecting functionally correlated proteins in biology to finding people to give discounts and gain maximum popularity of a product in economics. Thus, understanding and further being able to manipulate/control the development and evolution of the networks become critical tasks for network scientists. Despite the vast research effort putting towards these studies, the present state-of-the-arts largely either lack of high quality solutions or require excessive amount of time in real-world `Big Data\u27 requirement.
This research aims at affirmatively boosting the modern algorithmic efficiency to approach practical requirements. That is developing a ground-breaking class of algorithms that provide simultaneously both provably good solution qualities and low time and space complexities. Specifically, I target the important yet challenging problems in the three main areas:
Information Diffusion: Analyzing and maximizing the influence in networks and extending results for different variations of the problems.
Community Detection: Finding communities from multiple sources of information.
Security and Privacy: Assessing organization vulnerability under targeted-cyber attacks via social networks
The Solution Distribution of Influence Maximization: A High-level Experimental Study on Three Algorithmic Approaches
Influence maximization is among the most fundamental algorithmic problems in
social influence analysis. Over the last decade, a great effort has been
devoted to developing efficient algorithms for influence maximization, so that
identifying the ``best'' algorithm has become a demanding task. In SIGMOD'17,
Arora, Galhotra, and Ranu reported benchmark results on eleven existing
algorithms and demonstrated that there is no single state-of-the-art offering
the best trade-off between computational efficiency and solution quality.
In this paper, we report a high-level experimental study on three
well-established algorithmic approaches for influence maximization, referred to
as Oneshot, Snapshot, and Reverse Influence Sampling (RIS). Different from
Arora et al., our experimental methodology is so designed that we examine the
distribution of random solutions, characterize the relation between the sample
number and the actual solution quality, and avoid implementation dependencies.
Our main findings are as follows: 1. For a sufficiently large sample number, we
obtain a unique solution regardless of algorithms. 2. The average solution
quality of Oneshot, Snapshot, and RIS improves at the same rate up to scaling
of sample number. 3. Oneshot requires more samples than Snapshot, and Snapshot
requires fewer but larger samples than RIS. We discuss the time efficiency when
conditioning Oneshot, Snapshot, and RIS to be of identical accuracy. Our
conclusion is that Oneshot is suitable only if the size of available memory is
limited, and RIS is more efficient than Snapshot for large networks; Snapshot
is preferable for small, low-probability networks.Comment: To appear in SIGMOD 202
DySuse: Susceptibility Estimation in Dynamic Social Networks
Influence estimation aims to predict the total influence spread in social
networks and has received surged attention in recent years. Most current
studies focus on estimating the total number of influenced users in a social
network, and neglect susceptibility estimation that aims to predict the
probability of each user being influenced from the individual perspective. As a
more fine-grained estimation task, susceptibility estimation is full of
attractiveness and practical value. Based on the significance of susceptibility
estimation and dynamic properties of social networks, we propose a task, called
susceptibility estimation in dynamic social networks, which is even more
realistic and valuable in real-world applications. Susceptibility estimation in
dynamic networks has yet to be explored so far and is computationally
intractable to naively adopt Monte Carlo simulation to obtain the results. To
this end, we propose a novel end-to-end framework DySuse based on dynamic graph
embedding technology. Specifically, we leverage a structural feature module to
independently capture the structural information of influence diffusion on each
single graph snapshot. Besides, {we propose the progressive mechanism according
to the property of influence diffusion,} to couple the structural and temporal
information during diffusion tightly. Moreover, a self-attention block {is
designed to} further capture temporal dependency by flexibly weighting
historical timestamps. Experimental results show that our framework is superior
to the existing dynamic graph embedding models and has satisfactory prediction
performance in multiple influence diffusion models.Comment: This paper has been published in Expert Systems With Application
Generalized Partial Directed Coherence and centrality measures in brain networks for epileptogenic focus localization
Accurate epileptogenic focus localization is required prior to surgical resection of brain tissue for treatment of patients with intractable temporal lobe epilepsy, a clinical need that is partially fulfilled to date through a subjective, and at times inconclusive, evaluation of the recorded electroencephalogram (EEG). Using brain connectivity analysis, patterns of causal interactions between brain regions were derived from multichannel EEG of 127 seizures in nine patients with focal, temporal lobe epilepsy (TLE). The statistically significant directed interactions in the reconstructed brain networks were estimated from three second intracranial multi-electrode EEG segments using the Generalized Partial Directed Coherence (GPDC) and validated by surrogate data analysis. A set of centralities per network node were then estimated. Compared to extra-focal brain regions, regions located anatomically within the epileptogenic focus (focal regions) were found to be associated with enhanced inward directed centrality values at high frequencies (y band) during the initial segments of seizures (within nine seconds from seizures onset) and led to correct localization of the epileptogenic focus in all nine patients. Therefore, an immediate application of the employed novel network framework of analysis to intracranial EEG recordings may lead to a computerized, accurate and objective localization of the epileptogenic focus from ictal periods. The proposed framework could also pave the way for studies into network dynamics of the epileptogenic focus peri-ictally and interictally, which may have a significant impact on current automated seizure prediction and control applications
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