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Explore the fundamental theorem and proofs of DS decompositions for submodular functions in social networks. Discover applications like viral marketing, rumor source detection, and composed influence studies. Learn the upper bounds and differences in influence spread. Delve into the concepts of active friending on LinkedIn and the Kempe-Kleinberg-Tardos Conjecture.
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DS Decomposition Lecture 2-1
Fundamental Theorem MukundNarasimhan, Jeff A. Bilmes: A Submodular-supermodular Procedure with Applications to Discriminative Structure Learning. UAI 2005: 404-412 RishabhIyer and Jeff Bilmes: Algorithm for approximate Minimization of the difference between submodular functions, with application, arXiv:1207.0560v4 24 August 2013
Weak Version Proof
Any Submodular Function Proof
Fundamental Theorem Proof
Open Problem • Given a set function, there are many DS decompositions for it. • Given a set function, can we find a DS function for it efficiently?
Theorem Proof
Examples Lecture 1-2
1st Example Viral Marketing of Games
Upper Bound Lemma 1
Wang, Zhefeng, et al. "Activity Maximization by Effective Information Diffusion in Social Networks." IEEE Transactions on Knowledge and Data Engineering 29.11 (2017): 2374-2387.
2nd Example Find Effector
“Rumor” Source • Finding sources of activation is an important issue. • Given social network and diffusion model as well as all active nodes, find k effectors which best fit for the role of sources..
Problem Formulation Theorem
3rd Example Composed Influence
Problem • Two or more active persons together may give stronger influence than individual. • Composed influence can be formulated into hyper-edge. • With composed influence, the influence spread is neither submodular nor supermodular.
Submodular Upper Bound • Create “super nodes” representing the start node of super-edges. • Add edges from nodes contained in super-node to the super nodes. • A super node is active if it contains at least one active node.
Difference • What is the difference between upper bound and influence spread? • At least one super node is activated by an active node together with an inactive node.
DS Decomposition of the difference • By the inclusive-exclusive formula, the difference between the upper bound and the influence spread can be expressed as MC IC
Kempe-Kleinberg-Tardos Conjecture This conjecture is proved by Mossel and Roch in 2007 (STOC’07)
The 4th Example Active Friending
LinkedIn • Do you receive invitations from LinkedIn everyday? • Does LinkedIn have the following function: LinkedIn may suggest a list of invitations when you want to include a target person into friend list.
Problem Formulation Theorem