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 submodular maximization


Non-monotone Submodular Optimization: p-Matchoid Constraints and Fully Dynamic Setting

Neural Information Processing Systems

Submodular maximization subject to a p-matchoid constraint has various applications in machine learning, particularly in tasks such as feature selection, video and text summarization, movie recommendation, graph-based learning, and constraintbased optimization. We study this problem in the dynamic setting, where a sequence of insertions and deletions of elements to a p-matchoid M(V,I) occurs over time and the goal is to efficiently maintain an approximate solution. We propose a dynamic algorithm for non-monotone submodular maximization under a p-matchoid constraint. For a p-matchoid M(V,I) of rank k, defined by a collection of m matroids, our algorithm guarantees a (2p +2 p p(p +1) +1 +ฯต)-approximate solution at any time t in the update sequence, with an expected amortized query complexity of O(ฯต 3 pk4 log2(k)) per update.


GIST: Greedy Independent Set Thresholding for Max-Min Diversification with Submodular Utility

Neural Information Processing Systems

This work studies a novel subset selection problem called max-min diversification with monotone submodular utility (MDMS), which has a wide range of applications in machine learning, e.g., data sampling and feature selection. Given a set of points in a metric space, the goal of MDMS is to maximize f(S) = g(S)+ฮป div(S) subject to a cardinality constraint |S| k, where g(S)is a monotone submodular function and div(S) = minu,v S:u =v dist(u,v)is the max-min diversity objective. We propose the GIST algorithm, which gives a 1/2-approximation guarantee for MDMS by approximating a series of maximum independent set problems with a bicriteria greedy algorithm. We also prove that it is NP-hard to approximate within a factor of 0.5584. Finally, we show in our empirical study that GISToutperforms state-of-the-art benchmarks for a single-shot data sampling task on ImageNet.


Online Two-Stage Submodular Maximization

Neural Information Processing Systems

Given a collection of monotone submodular functions, the goal of Two-Stage Submodular Maximization (2SSM) [Balkanski et al., 2016] is to restrict the ground set so an objective selected u.a.r.


Improved Algorithms for Online Submodular Maximization via First-order Regret Bounds

Neural Information Processing Systems

We consider the problem of nonnegative submodular maximization in the online setting. At time step t, an algorithm selects a set St C 2V where C is a feasible family of sets. An adversary then reveals a submodular function ft. The goal is to design an efficient algorithm for minimizing the expected approximate regret. In this work, we give a general approach for improving regret bounds in online submodular maximization by exploiting "first-order" regret bounds for online linear optimization. For monotone submodular maximization subject to a matroid, we give an efficient algorithm which achieves a (1 c/e ฮต)-regret of O( p kTln(n/k)) where n is the size of the ground set, k is the rank of the matroid, ฮต > 0 is a constant, and cis the average curvature. Even without assuming any curvature (i.e., taking c = 1), this regret bound improves on previous results of Streeter et al. (2009) and Golovin et al. (2014). For nonmonotone, unconstrained submodular functions, we give an algorithm with 1/2-regret O( nT), improving on the results of Roughgarden and Wang (2018). Our approach is based on Blackwell approachability; in particular, we give a novel first-order regret bound for the Blackwell instances that arise in this setting.


Submodular Cover Problem Bicriteria Approximation Algorithms for the

Neural Information Processing Systems

Another example is when expected advertising revenue if we set ฯ„ = max{f(X): X U}, SCP asks to find the set of minimum size in U that achieves measure how effectively a subset X summarizes the entire dataset U [Tschiatschek et al., 2014].