论文标题
在实践中自动锯齿形抽样
Automatic Zig-Zag sampling in practice
论文作者
论文摘要
在过去的十年中,新型的蒙特卡洛方法从目标分布中生成样品,例如贝叶斯分析的后部,迅速扩展。基于分段确定性马尔可夫过程(PDMP)的算法,非可逆的连续时间过程,正在发展为自己的研究分支,感谢其重要属性(例如,正确的不变分布,牙齿分布,牙齿和超级效率)。然而,实践尚未赶上该领域的理论,并且使用PDMP来解决应用问题并不普遍。首先,这可能是由于基于PDMP的几个实施挑战所带来的几个实施挑战,其次是缺乏在应用设置中展示方法和实现的论文。在这里,我们使用最有希望的PDMP之一,曲折ZAG采样器作为原型示例来解决这两个问题。在解释了Zig-Zag采样器的关键要素之后,其实施挑战被暴露和解决。具体而言,提供了从目标分布中汲取样品的算法的表述。值得注意的是,算法的唯一要求是评估目标密度的封闭形式功能,并且与以前的实现不同,不需要有关目标的进一步信息。算法的性能针对另一个基于梯度的采样器进行了评估,并在模拟和真实数据设置中被证明具有竞争力。最后,我们证明了超级效率属性,即以比评估所有数据的可能性要低的成本绘制一个独立样本的能力,可以在实践中获得。
Novel Monte Carlo methods to generate samples from a target distribution, such as a posterior from a Bayesian analysis, have rapidly expanded in the past decade. Algorithms based on Piecewise Deterministic Markov Processes (PDMPs), non-reversible continuous-time processes, are developing into their own research branch, thanks their important properties (e.g., correct invariant distribution, ergodicity, and super-efficiency). Nevertheless, practice has not caught up with the theory in this field, and the use of PDMPs to solve applied problems is not widespread. This might be due, firstly, to several implementational challenges that PDMP-based samplers present with and, secondly, to the lack of papers that showcase the methods and implementations in applied settings. Here, we address both these issues using one of the most promising PDMPs, the Zig-Zag sampler, as an archetypal example. After an explanation of the key elements of the Zig-Zag sampler, its implementation challenges are exposed and addressed. Specifically, the formulation of an algorithm that draws samples from a target distribution of interest is provided. Notably, the only requirement of the algorithm is a closed-form function to evaluate the target density of interest, and, unlike previous implementations, no further information on the target is needed. The performance of the algorithm is evaluated against another gradient-based sampler, and it is proven to be competitive, in simulation and real-data settings. Lastly, we demonstrate that the super-efficiency property, i.e. the ability to draw one independent sample at a lesser cost than evaluating the likelihood of all the data, can be obtained in practice.