论文标题
梯度平滑的功能算法,具有截短的cauchy随机扰动进行随机优化
A Gradient Smoothed Functional Algorithm with Truncated Cauchy Random Perturbations for Stochastic Optimization
论文作者
论文摘要
在本文中,我们提出了一种随机梯度算法,用于最大程度地减少对嘈杂成本样本的期望,而对于任何给定参数,就只能观察到后者。我们的算法采用带有随机扰动的梯度估计方案,该方案是使用从三角球体截断的cauchy分布形成的。我们分析了所提出的梯度估计器的偏差和方差。发现我们的算法在目标函数为非凸且参数维度很高的情况下特别有用。从渐近收敛分析中,我们确定我们的算法几乎可以肯定地收敛到目标函数的固定点并获得渐近收敛速率。我们还表明,我们的算法避免了不稳定的平衡,这意味着与局部最小值的融合。此外,我们对我们的算法进行非反应收敛分析。特别是,我们在这里建立了一个非质子绑定,用于寻找非凸目标函数的epsilon平台。最后,我们通过模拟以数值方式证明我们的算法的性能在一些非凸面设置上大大优于GSF,SPSA和RDSA,并进一步验证其在凸(Noisy)目标上的性能。
In this paper, we present a stochastic gradient algorithm for minimizing a smooth objective function that is an expectation over noisy cost samples, and only the latter are observed for any given parameter. Our algorithm employs a gradient estimation scheme with random perturbations, which are formed using the truncated Cauchy distribution from the delta sphere. We analyze the bias and variance of the proposed gradient estimator. Our algorithm is found to be particularly useful in the case when the objective function is non-convex, and the parameter dimension is high. From an asymptotic convergence analysis, we establish that our algorithm converges almost surely to the set of stationary points of the objective function and obtains the asymptotic convergence rate. We also show that our algorithm avoids unstable equilibria, implying convergence to local minima. Further, we perform a non-asymptotic convergence analysis of our algorithm. In particular, we establish here a non-asymptotic bound for finding an epsilon-stationary point of the non-convex objective function. Finally, we demonstrate numerically through simulations that the performance of our algorithm outperforms GSF, SPSA, and RDSA by a significant margin over a few non-convex settings and further validate its performance over convex (noisy) objectives.