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- research-articleMay 2024
Projected Gaussian Markov Improvement Algorithm for High-Dimensional Discrete Optimization via Simulation
ACM Transactions on Modeling and Computer Simulation (TOMACS), Volume 34, Issue 3Article No.: 14, Pages 1–29https://doi.org/10.1145/3649463This article considers a discrete optimization via simulation (DOvS) problem defined on a graph embedded in the high-dimensional integer grid. Several DOvS algorithms that model the responses at the solutions as a realization of a Gaussian Markov random ...
- introductionMay 2024
- research-articleApril 2024
Stochastic Approximation for Multi-period Simulation Optimization with Streaming Input Data
ACM Transactions on Modeling and Computer Simulation (TOMACS), Volume 34, Issue 2Article No.: 6, Pages 1–27https://doi.org/10.1145/3617595We consider a continuous-valued simulation optimization (SO) problem, where a simulator is built to optimize an expected performance measure of a real-world system while parameters of the simulator are estimated from streaming data collected periodically ...
- research-articleFebruary 2024
A Shrinkage Approach to Improve Direct Bootstrap Resampling Under Input Uncertainty
INFORMS Journal on Computing (INFORMS-IJOC), Volume 36, Issue 4Pages 1023–1039https://doi.org/10.1287/ijoc.2022.0044Discrete-event simulation models generate random variates from input distributions and compute outputs according to the simulation logic. The input distributions are typically fitted to finite real-world data and thus are subject to estimation errors that ...
- research-articleFebruary 2024
Efficient Input Uncertainty Quantification for Regenerative Simulation
The initial bias in steady-state simulation can be characterized as the bias of a ratio estimator if the simulation model has a regenerative structure. This work tackles input uncertainty quantification for a regenerative simulation model when its input ...
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- research-articleOctober 2023
Using Cache or Credit for Parallel Ranking and Selection
ACM Transactions on Modeling and Computer Simulation (TOMACS), Volume 33, Issue 4Article No.: 12, Pages 1–28https://doi.org/10.1145/3618299In this article, we focus on ranking and selection procedures that sequentially allocate replications to systems by applying some acquisition function. We propose an acquisition function, called gCEI, which exploits the gradient of the complete expected ...
- research-articleMarch 2023
Object-Oriented Implementation and Parallelization of the Rapid Gaussian Markov Improvement Algorithm
WSC '22: Proceedings of the Winter Simulation ConferencePages 3158–3169The Rapid Gaussian Markov Improvement Algorithm (rGMIA) solves discrete optimization via simulation problems by using a Gaussian Markov random field and complete expected improvement as the sampling and stopping criterion. rGMIA has been created as a ...
- research-articleMarch 2023
Optimizing Input Data Acquisition for Ranking and Selection: A View through the Most Probable Best
WSC '22: Proceedings of the Winter Simulation ConferencePages 2258–2269This paper concerns a Bayesian ranking and selection (R&S) problem under input uncertainty when all solutions are simulated with common input models estimated from data. We assume that there are multiple independent input data sources from which ...
- research-articleFebruary 2022
Nonparametric kullback-liebler divergence estimation using m-spacing
WSC '21: Proceedings of the Winter Simulation ConferenceArticle No.: 185, Pages 1–12Entropy of a random variable with unknown distribution function can be estimated nonparametrically by spacing methods when independent and identically distributed (i.i.d.) observations of the random variable are available. We extend the classical ...
- research-articleFebruary 2022
Selection of the most probable best under input uncertainty
WSC '21: Proceedings of the Winter Simulation ConferenceArticle No.: 180, Pages 1–12We consider a ranking and selection problem whose configuration depends on a common input model estimated from finite real-world observations. To find a solution robust to estimation error in the input model, we introduce a new concept of robust ...
- research-articleJuly 2021
Rapid Discrete Optimization via Simulation with Gaussian Markov Random Fields
INFORMS Journal on Computing (INFORMS-IJOC), Volume 33, Issue 3Pages 915–930https://doi.org/10.1287/ijoc.2020.0971Inference-based optimization via simulation, which substitutes Gaussian process (GP) learning for the structural properties exploited in mathematical programming, is a powerful paradigm that has been shown to be remarkably effective in problems of modest ...
- research-articleMay 2021
Smart linear algebraic operations for efficient Gaussian Markov improvement algorithm
WSC '20: Proceedings of the Winter Simulation ConferencePages 2887–2898This paper studies computational improvement of the Gaussian Markov improvement algorithm (GMIA) whose underlying response surface model is a Gaussian Markov random field (GMRF). GMIA's computational bottleneck lies in the sampling decision, which ...
- research-articleJuly 2020
Uncertainty Quantification in Vehicle Content Optimization for General Motors
A vehicle content portfolio refers to a complete set of combinations of vehicle features offered while satisfying certain restrictions for the vehicle model. Vehicle Content Optimization (VCO) is a simulation-based decision support system at General ...
- research-articleMay 2020
Efficient input uncertainty quantification via green simulation using sample path likelihood ratios
WSC '19: Proceedings of the Winter Simulation ConferencePages 3693–3704Bootstrapping is a popular tool for quantifying input uncertainty, inflated uncertainty in the simulation output caused by finite-sample estimation error in the input models. Typical bootstrap-based procedures have a nested simulation structure that ...
- research-articleMay 2020
Stochastic approximation for simulation optimization under input uncertainty with streaming data
WSC '19: Proceedings of the Winter Simulation ConferencePages 3597–3608We consider a simulation optimization problem whose objective function is defined as the expectation of a simulation output based on a continuous decision variable, where the parameters of the simulation input distributions are estimated based on ...
- research-articleMarch 2019
Input–Output Uncertainty Comparisons for Discrete Optimization via Simulation
Selecting the optimal policy using simulation is subject to input model risk when input models that mimic real-world randomness in the simulation have estimation error due to finite sample sizes. Instead of trying to find the optimal solution under ...
When input distributions to a simulation model are estimated from real-world data, they naturally have estimation error causing input uncertainty in the simulation output. If an optimization via simulation (OvS) method is applied that treats the input ...
- research-articleJanuary 2019
Gaussian Markov Random Fields for Discrete Optimization via Simulation: Framework and Algorithms
This paper lays the foundation for employing Gaussian Markov random fields (GMRFs) for discrete decision–variable optimization via simulation; that is, optimizing the performance of a simulated system. Gaussian processes have gained popularity for ...
We consider optimizing the expected value of some performance measure of a dynamic stochastic simulation with a statistical guarantee for optimality when the decision variables are discrete, in particular, integer-ordered; the number of feasible solutions ...
- research-articleDecember 2018
Generalized method of moments approach to hyperparameter estimation for Gaussian Markov random fields
When a Gaussian Markov random field (GMRF) is used as a metamodel of an unknown response surface for a discrete optimization via simulation (DOvS) problem, the hyperparameters of the GMRF are estimated based on a few initial design points in a large ...
- research-articleDecember 2018
Revisiting direct bootstrap resampling for input model uncertainty
Metamodel-based bootstrap methods for characterizing input model uncertainty have disadvantages for settings where there are a large number of input distributions, or when using empirical distributions to drive the simulation. Early direct bootstrapping ...
- research-articleDecember 2017
Computational methods for optimization via simulation using gaussian markov random fields
WSC '17: Proceedings of the 2017 Winter Simulation ConferenceArticle No.: 164, Pages 1–12There has been recent interest, and significant success, in adapting and extending ideas from statistical learning via Gaussian process (GP) regression to optimization via simulation (OvS) problems. At the heart of all such methods is a GP representing ...