从均匀随机解中学习k-CNF公式,样本量大幅降低
Learning CNF formulas from uniform random solutions in the local lemma regime
- 基于洛瓦兹局部引理条件,用极少样本精确还原有界交集的k-CNF
- 在可满足性阈值附近,仅需约n^{exp(-√k)}样本即可学习
- 适用于需要高效布尔模型学习的研究者,如机器学习与理论计算机
我们研究从独立同分布的均匀随机解中学习n变量k-CNF公式Φ的问题,这等价于学习具有k元硬约束的布尔马尔可夫随机场(MRF)。重访Valiant算法(Commun. ACM'84),我们证明该算法可在洛瓦兹局部引理型条件下,仅用O(log n)样本精确学习具有有界子句交集的k-CNF;同时,在可满足性阈值附近,仅需˜O(n^{exp(-√k)})样本即可学习随机k-CNF。这些结果显著优于此前O(n^k)的样本复杂度。我们进一步建立了在独立同分布均匀随机解下,精确与近似学习的信息论下界。
原文摘要 · Abstract (English)
We study the problem of learning a $n$-variables $k$-CNF formula $Φ$ from its i.i.d. uniform random solutions, which is equivalent to learning a Boolean Markov random field (MRF) with $k$-wise hard constraints. Revisiting Valiant's algorithm (Commun. ACM'84), we show that it can exactly learn (1) $k$-CNFs with bounded clause intersection size under Lovász local lemma type conditions, from $O(\log n)$ samples; and (2) random $k$-CNFs near the satisfiability threshold, from $\widetilde{O}(n^{\exp(-\sqrt{k})})$ samples. These results significantly improve the previous $O(n^k)$ sample complexity. We further establish new information-theoretic lower bounds on sample complexity for both exact and approximate learning from i.i.d. uniform random solutions.
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