A Finite Time Analysis of Two Time-Scale Actor Critic Methods

Actor-critic (AC) methods have exhibited great empirical success compared with other reinforcement learning algorithms, where the actor uses the policy gradient to improve the learning policy and the critic uses temporal difference learning to estimate the policy gradient. Under the two time-scale learning rate schedule, the asymptotic convergence of AC has been well studied in the literature. However, the non-asymptotic convergence and finite sample complexity of actor-critic methods are largely open. In this work, we provide a non-asymptotic analysis for two time-scale actor-critic methods under non-i.i.d. setting. We prove that the actor-critic method is guaranteed to find a first-order stationary point (i.e., $\|\nabla J(\boldsymbol{\theta})\|_2^2 \le \epsilon$) of the non-concave performance function $J(\boldsymbol{\theta})$, with $\mathcal{\tilde{O}}(\epsilon^{-2.5})$ sample complexity. To the best of our knowledge, this is the first work providing finite-time analysis and sample complexity bound for two time-scale actor-critic methods.Comment: 45 page

Chinese Graduate Students’ Perceptions of Classroom Assessment at a Canadian University

The purpose of this study was to investigate Chinese graduate students’ perceptions of classroom assessment at a Canadian university. Data collection for the study was comprised of two parts: an online survey for the collection of quantitative data, and semi-structured interviews for the collection of qualitative data. Sixty-two participants (n=62) voluntarily finished the online questionnaire and ten interview participants took part in semi-structured interviews. The exploration into the participants illustrated that Chinese graduate students held positive perceptions of classroom assessment at the Canadian university where the study was conducted, in terms of congruence with planned learning, authenticity, student consultation, transparency, and diversity. However, the lower values for student consultation and diversity imply that students were not consulted and informed adequately about the forms of assessment tasks being employed, and teachers were not adequately concerned about students’ diversity with regard to issues such as students’ different abilities and the time required to finish their assessments. Also, there were no significant differences in Chinese graduate students’ perceptions of classroom assessment by gender, program of study, and year in the program, but significant differences in their perceptions by self-perceived level of English proficiency. Finally, in order to enhance students’ learning and motivation to learn, the research suggested that six factors of classroom assessment should be emphasized: timeliness, score, authenticity, forms of assessment, assessment guidance, and assessment feedback

General Aviation Airports: Innovative Revenue Strategies

General aviation airports face increasing financial pressures. The more than 2,900 GA airports in the U.S. are very important to the national transportation system and serve other societal needs as well. This presentation contains six innovative strategies for revenue generation and discusses a decision-making process for airport operators to use to select the best revenue generation strategy for their airport