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arXiv · 1007.1229

Submodularity on a tree: Unifying $L^\natural$-convex and bisubmodular functions

Vladimir Kolmogorov
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Abstract

We introduce a new class of functions that can be minimized in polynomial time in the value oracle model. These are functions $f$ satisfying $f(x)+f(y)\ge f(x \sqcap y)+f(x \sqcup y)$ where the domain of each variable $x_i$ corresponds to nodes of a rooted binary tree, and operations $\sqcap,\sqcup$ are defined with respect to this tree. Special cases include previously studied $L^\natural$-convex and bisubmodular functions, which can be obtained with particular choices of trees. We present a polynomial-time algorithm for minimizing functions in the new class. It combines Murota's steepest descent algorithm for $L^\natural$-convex functions with bisubmodular minimization algorithms.

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Vladimir Kolmogorov. 2011-04-14. Submodularity on a tree: Unifying $L^\natural$-convex and bisubmodular functions. https://arxiv.org/abs/1007.1229

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