Search Results for author: Yasong Feng

Found 7 papers, 1 papers with code

From Random Search to Bandit Learning in Metric Measure Spaces

no code implementations19 May 2023 Chuying Han, Yasong Feng, Tianyu Wang

We show that, when the environment is noise-free, the output of random search converges to the optimal value in probability at rate $ \widetilde{\mathcal{O}} \left( \left( \frac{1}{T} \right)^{ \frac{1}{d_s} } \right) $, where $ d_s \ge 0 $ is the scattering dimension of the underlying function.

Hyperparameter Optimization

Convergence Rates of Stochastic Zeroth-order Gradient Descent for Ł ojasiewicz Functions

no code implementations31 Oct 2022 Tianyu Wang, Yasong Feng

We prove convergence rates of Stochastic Zeroth-order Gradient Descent (SZGD) algorithms for Lojasiewicz functions.

Stochastic Zeroth Order Gradient and Hessian Estimators: Variance Reduction and Refined Bias Bounds

1 code implementation29 May 2022 Yasong Feng, Tianyu Wang

In particular, we design estimators for smooth functions such that, if one uses $ \Theta \left( k \right) $ random directions sampled from the Stiefel's manifold $ \text{St} (n, k) $ and finite-difference granularity $\delta$, the variance of the gradient estimator is bounded by $ \mathcal{O} \left( \left( \frac{n}{k} - 1 \right) + \left( \frac{n^2}{k} - n \right) \delta^2 + \frac{ n^2 \delta^4 }{ k } \right) $, and the variance of the Hessian estimator is bounded by $\mathcal{O} \left( \left( \frac{n^2}{k^2} - 1 \right) + \left( \frac{n^4}{k^2} - n^2 \right) \delta^2 + \frac{n^4 \delta^4 }{k^2} \right) $.

A More Stable Accelerated Gradient Method Inspired by Continuous-Time Perspective

no code implementations9 Dec 2021 Yasong Feng, Weiguo Gao

Experiments of matrix completion and handwriting digit recognition demonstrate that the stability of our new method is better.

Matrix Completion

Lipschitz Bandits with Batched Feedback

no code implementations19 Oct 2021 Yasong Feng, Zengfeng Huang, Tianyu Wang

Specifically, we show that for a $T$-step problem with Lipschitz reward of zooming dimension $d_z$, our algorithm achieves theoretically optimal (up to logarithmic factors) regret rate $\widetilde{\mathcal{O}}\left(T^{\frac{d_z+1}{d_z+2}}\right)$ using only $ \mathcal{O} \left( \log\log T\right) $ batches.

A new accelerated gradient method inspired by continuous-time perspective

no code implementations1 Jan 2021 Yasong Feng, Weiguo Gao

To give more insight about the acceleration phenomenon, an ordinary differential equation was obtained from Nesterov's accelerated method by taking step sizes approaching zero, and the relationship between Nesterov's method and the differential equation is still of research interest.

Matrix Completion

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