arXiv:2509.16769cs.LGcs.AI2025-09

用多平面混合建模类别,兼顾准确率、可解释性和速度。

Geometric Mixture Classifier (GMC): A Discriminative Per-Class Mixture of Hyperplanes

  • 每类由多个超平面混合构成,通过温度控制的软最大值融合得分。
  • 在多个数据集上超越线性模型,接近核方法与小规模神经网络性能。
  • 支持可视化每个平面的责任归属,适合需要透明决策过程的场景。

现实世界中的类别常呈多模态分布,单个类别在特征空间中占据不连续区域。传统线性模型(如逻辑回归、线性SVM)使用单一全局超平面,难以处理此类数据;而高容量方法(如核SVM、深度网络)虽能拟合复杂结构,但牺牲了可解释性、需更多调参且计算开销大。本文提出几何混合分类器(GMC),将每类表示为一组超平面的混合。类内通过温度调控的软-或(log-sum-exp)融合各平面得分,平滑逼近最大值;类间采用标准softmax生成概率后验。GMC可选随机傅里叶特征(RFF)实现非线性映射,同时保持推理阶段对平面数和特征数线性扩展。训练策略包括:几何感知k均值初始化、轮廓系数驱动的平面数量分配、α退火、使用感知L2正则化、标签平滑与早停,使GMC即插即用。在合成多模态数据集(月亮、圆环、聚块、螺旋)及表格/图像基准(iris、wine、WDBC、digits)上,GMC持续优于线性基线和kNN,性能媲美RBF-SVM、随机森林与小型MLP,且可通过每平面责任可视化提供几何洞察。推理时间随平面与特征线性增长,单样本延迟为亚毫秒级,通常快于RBF-SVM与紧凑型MLP。后验温度校准将ECE从约0.06降至0.02。GMC在精度、可解释性与效率间取得良好平衡:比线性模型更灵活,又比核或深层模型更轻量、透明、快速。

原文摘要 · Abstract (English)

Many real world categories are multimodal, with single classes occupying disjoint regions in feature space. Classical linear models (logistic regression, linear SVM) use a single global hyperplane and perform poorly on such data, while high-capacity methods (kernel SVMs, deep nets) fit multimodal structure but at the expense of interpretability, heavier tuning, and higher computational cost. We propose the Geometric Mixture Classifier (GMC), a discriminative model that represents each class as a mixture of hyperplanes. Within each class, GMC combines plane scores via a temperature-controlled soft-OR (log-sum-exp), smoothly approximating the max; across classes, standard softmax yields probabilistic posteriors. GMC optionally uses Random Fourier Features (RFF) for nonlinear mappings while keeping inference linear in the number of planes and features. Our practical training recipe: geometry-aware k-means initialization, silhouette-based plane budgeting, alpha annealing, usage-aware L2 regularization, label smoothing, and early stopping, makes GMC plug-and-play. Across synthetic multimodal datasets (moons, circles, blobs, spirals) and tabular/image benchmarks (iris, wine, WDBC, digits), GMC consistently outperforms linear baselines and k-NN, is competitive with RBF-SVM, Random Forests, and small MLPs, and provides geometric introspection via per-plane and class responsibility visualizations. Inference scales linearly in planes and features, making GMC CPU-friendly, with single-digit microsecond latency per example, often faster than RBF-SVM and compact MLPs. Post-hoc temperature scaling reduces ECE from about 0.06 to 0.02. GMC thus strikes a favorable balance of accuracy, interpretability, and efficiency: it is more expressive than linear models and lighter, more transparent, and faster than kernel or deep models.

分类器可解释性高效推理

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