Motivated by batch and semi-batch process operation, we study finite-horizon open-loop dynamic optimization problems with uncertain parameters. A common computational approach replaces the expected performance criterion by an average over finitely many sampled parameter realizations. We develop a statistical theory for the resulting sample-based optimal value as an estimator of the population optimal value. The analysis is based on a stability estimate showing that terminal losses depend Lipschitz continuously on the time-integrated control, which records the cumulative input delivered up to each time. This estimate yields a functional central limit theorem for the sample-based objective and a statistical limit theorem for the corresponding optimal value error. As a consequence, we obtain confidence intervals for the population optimal value. When the population optimizer is unique, the limit is Gaussian and leads to a plug-in confidence interval. When multiple optimal policies may exist, we use a subsampling confidence interval that does not require uniqueness. The methodology is illustrated on two fed-batch case studies in which feed-rate profiles are optimized under parametric uncertainty.
It is shown that the approximate value functions obtained by value iteration and LP asymptotically converge to the optimal value function, and the policies generated by policy iteration converge in value to an optimal policy.
J. Zhang, Saumya Sinha, Mehdi Hemmati et al.· 0 citations
This work establishes finite-time rates of $\tilde{O} (1/\sqrt{n})$ for the aforementioned two algorithms under asynchronous Markovian sampling, where $n$ is the iteration index and $\tilde{O}$ hides logarithmic expressions.
Ankur Naskar, A. VivekT, Aditya Kumar et al.· 0 citations
A zeroth-order algorithm is developed that uses sampled losses to construct empirical CVaR estimates and their gradient estimates and establishes a finite-time expected suboptimality bound for the weighted ergodic iterate.
A line-search-free and function-value-free adaptive projected-gradient algorithm for the sample-average approximation (SAA) problem that transfers vanishing SAA residuals to Pareto stationarity for the population problem, while an additional concentration argument gives a finite-sample residual bound on compact sets.
The results show that the possibility of combining consistency and robustness in robust scheduling depends critically on the interaction between the uncertainty model and the machine environment, and the interaction between the uncertainty model and the machine environment.
Yasser Alghouass, Eric Balkanski, Nicole Megow et al.· 0 citations
This work treats the evolving SGD trajectory as a sequential experiment whose observations provide evidence about the unknown optimization error, and develops new recursive confidence-sequence techniques and a general time-uniform empirical Bernstein inequality for adapted processes with time-varying conditional means...
Liviu Aolaritei, Lucas Lévy, Francis R. Bach et al.· 0 citations
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