arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2311.03332cs.LGcs.DSmath.STstat.MLstat.TH
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基于单样本学习硬约束模型

Learning Hard-Constrained Models with One Sample

University of Oxford(牛津大学);Yale University(耶鲁大学);MIT(麻省理工学院)

Andreas Galanis, Alkis Kalavasis, Anthimos Vardis Kandiros

AI总结:

该研究针对单样本硬约束马尔可夫随机场参数估计问题,基于伪似然估计器与耦合技术,给出了$k$-SAT、$q$-着色及$H$-着色模型的可估条件与线性时间算法,同时证明了若干不可识别情形。

摘要:

我们研究使用单个样本估计带硬约束的马尔可夫随机场参数的问题。作为主要的运行示例,我们采用$k$-SAT、正常着色模型以及通用的$H$-着色模型;针对所有这些模型,我们同时得到了正面和负面结果。与软约束情形不同,我们特别证明了单样本估计并非始终可行,且估计器的存在性与不可满足实例的存在性相关。\n我们的算法基于伪似然估计器。对于$k$-SAT,我们受Moitra采样算法(JACM, 2019)启发,采用耦合技术证明了该估计器的方差界;我们针对着色问题的正面结果建立在这种新的耦合方法之上。对于最大度为$d$的图上的$q$-着色问题,当$q>d+1$时我们给出了一个线性时间估计器,而当$q\leq d+1$时该问题是不可识别的。对于通用$H$-着色问题,我们证明了保证采样的标准条件(如Dobrushin条件)不足以实现单样本学习;在正面结果方面,我们给出了一个足以保证线性时间学习的通用条件,并得到了其在正常着色和容许模型中的应用。对于最大度为$d$的公式上的$k$-SAT模型,当$k\gtrsim 6.45\log d$时我们提供了一个线性时间估计器,而当$k\lesssim \log d$时该问题变得不可识别。

英文摘要:

We consider the problem of estimating the parameters of a Markov Random Field with hard-constraints using a single sample. As our main running examples, we use the $k$-SAT and the proper coloring models, as well as general $H$-coloring models; for all of these we obtain both positive and negative results. In contrast to the soft-constrained case, we show in particular that single-sample estimation is not always possible, and that the existence of an estimator is related to the existence of non-satisfiable instances. Our algorithms are based on the pseudo-likelihood estimator. We show variance bounds for this estimator using coupling techniques inspired, in the case of $k$-SAT, by Moitra's sampling algorithm (JACM, 2019); our positive results for colorings build on this new coupling approach. For $q$-colorings on graphs with maximum degree $d$, we give a linear-time estimator when $q>d+1$, whereas the problem is non-identifiable when $q\leq d+1$. For general $H$-colorings, we show that standard conditions that guarantee sampling, such as Dobrushin's condition, are insufficient for one-sample learning; on the positive side, we provide a general condition that is sufficient to guarantee linear-time learning and obtain applications for proper colorings and permissive models. For the $k$-SAT model on formulas with maximum degree $d$, we provide a linear-time estimator when $k\gtrsim 6.45\log d$, whereas the problem becomes non-identifiable when $k\lesssim \log d$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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