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Solomonovi seminarji

Modeling real-world networks using Kronecker multiplication

author: Jure Leskovec, IJS

Description

Given a large, real graph, how can we generate a synthetic graph that matches its properties, i.e., it has similar degree distribution, similar (small) diameter, similar spectrum, etc? First, we propose a graph generator that is mathematically tractable and generates realistic graphs. The main idea is to use a non-standard matrix operation, the Kronecker product, to generate graphs that we refer to as ``Kronecker graphs''. We show that Kronecker graphs naturally obey all the above properties; in fact, we can rigorously prove that they do so. Once we have the model, we fit it to real graph to generate a synthetic graph that matches its properties, i.e., it has similar degree distribution, similar (small) diameter, similar spectrum, etc? We present a fast and scalable algorithm for fitting the Kronecker graph generation model to real networks. A naive approach to fitting would take super-exponential time. In contrast, our algorithm takes linear time, by exploiting the structure of Kronecker matrix multiplication and by using sampling. Experiments on large real and synthetic graphs show that our approach recovers the true parameters and indeed mimics very well the patterns found in the target graphs. Once fitted, the model parameters and the resulting synthetic graphs can be used for anonymization, extrapolations, and graph summarization.

The presentation starts in Slovenian language and switches to English a few minutes into the lecture.
Another lecture on the same topic can be found at /icml07_leskovec_smrg/.

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Slides
0:03 Modeling networks using Kronecker multiplication
0:37 Introduction
2:40 New approach (1)
4:26 New approach (2)
4:54 Outline
4:58 Outline
5:14 Statistical properties of networks
6:11 Small-world effect (1)
7:52 Small-world effect (2)
8:51 Degree distributions (1)
9:52 Degree distributions (2)
10:31 Degree distributions (3)
11:48 Poisson vs. Scale-free network
21:19 Spectral properties
22:14 Temporal Graph Patterns
22:26 Temporal Patterns – Densification
23:23 Networks over time: Densification
24:07 Densification & degree distribution
24:10 Shrinking diameters
24:55 Patterns hold in many graphs
25:51 Outline
26:10 Graph Generators
27:02 Kronecker graphs
27:30 Recursive Graph Generation
27:43 Kronecker Product – a Graph
28:52 Kronecker Product – a Graph
28:59 Kronecker Graphs – Formally:
29:16 Kronecker Product – a Graph
29:20 Kronecker Graphs – Formally:
29:27 Kronecker Product – Definition
29:46 Kronecker Graphs
29:53 Kronecker Graphs – Intuition
30:15 How to randomize a graph?
30:20 Kronecker Product – a Graph
30:27 Stochastic Kronecker Graphs
31:12 Outline
31:20 Problem Definition
31:42 Outline
32:02 Why fitting generative models?
32:55 Problem definition
33:54 Fitting Kronecker to Real Data
36:19 Challenge 1: Node labeling
37:49 Challenge 2: calculating P(G|Θ,σ)
38:59 Our solutions
41:39 Sampling node labelings (1)
42:36 Sampling node labelings (2)
47:33 Calculating P(G|Θ,σ)
50:11 Convergence of fitting
56:53 AS graph (N=6500, E=26500)
58:13 Epinions graph (N=76k, E=510k)
62:16 Scalability
63:41 Model selection
69:00 Epinions graph (N=76k, E=510k)
70:37 Conclusion
75:40 AS graph (N=6500, E=26500)
76:10 Epinions graph (N=76k, E=510k)

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