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DS Decomposition. Lecture 2-1. Fundamental Theorem. Mukund Narasimhan , Jeff A. Bilmes : A Submodular- supermodular Procedure with Applications to Discriminative Structure Learning. UAI 2005 : 404-412
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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