arXiv:2512.15198cs.AImath.OC2025-12

通过聚类分组变量,提升松弛决策图求解最大权独立集的效率。

A Clustering-Based Variable Ordering Framework for Relaxed Decision Diagrams for Maximum Weighted Independent Set Problem

  • 将变量聚类后分组排序,缩小动态排序搜索空间。
  • 在基准测试中,计算成本显著低于传统动态排序方法。
  • 适合需要高效精确求解离散优化问题的研究者使用。

离散优化(DO)的高效精确算法依赖于强的原始和对偶界。松弛决策图(DDs)通过节点合并紧凑地过逼近解空间,从而提供对偶界。然而,其质量(即对偶界的紧致性)高度依赖于变量顺序和编译过程中的合并决策。虽然动态变量排序启发式能有效收紧界,但全局评估所有未固定变量常带来计算开销。为此,本文提出一种基于聚类的变量排序新框架:先将变量划分为簇,再利用结构分解引导排序过程,大幅减少启发式搜索空间。研究了两种策略:簇间排序(按问题特定聚合标准,如最大权独立集问题中的累计顶点权重),以及选排序(从各簇中迭代选取并排序代表性变量,平衡局部多样性与启发式指导)。此外,基于最大权独立集问题中决策图大小增长的理论分析,提出了设置簇数的两种策略。将这些方法嵌入基于决策图的分支定界算法,在基准实例上评估表明,该方法相比标准动态排序基线能持续降低计算成本。

原文摘要 · Abstract (English)

Efficient exact algorithms for Discrete Optimization (DO) rely heavily on strong primal and dual bounds. Relaxed Decision Diagrams (DDs) provide a versatile mechanism for deriving such dual bounds by compactly over-approximating the solution space through node merging. However, the quality of these relaxed diagrams, i.e. the tightness of the resulting dual bounds, depends critically on the variable ordering and the merging decisions executed during compilation. While dynamic variable ordering heuristics effectively tighten bounds, they often incur computational overhead when evaluated globally across the entire variable set. To mitigate this trade-off, this work introduces a novel clustering-based framework for variable ordering. Instead of applying dynamic ordering heuristics to the full set of unfixed variables, we first partition variables into clusters. We then leverage this structural decomposition to guide the ordering process, significantly reducing the heuristic's search space. Within this framework, we investigate two distinct strategies: Cluster-to-Cluster, which processes clusters sequentially using problem-specific aggregate criteria (such as cumulative vertex weights in the Maximum Weighted Independent Set Problem (MWISP)), and Pick-and-Sort, which iteratively selects and sorts representative variables from each cluster to balance local diversity with heuristic guidance. Later on, developing some theoretical results on the growth of the size of DDs for MWISP we propose two different policies for setting the number of clusters within the proposed framework. We embed these strategies into a DD-based branch-and-bound algorithm and evaluate them on the MWISP. Across benchmark instances, the proposed methodology consistently reduces computational costs compared to standard dynamic variable ordering baseline.

决策图聚类离散优化最大权独立集

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