Professor and Department Head of Industrial and Systems Engineering
University of Minnesota - Twin Cities

207 Church Street SE, Minneapolis, MN 55455

Office: Lind Hall, 215

Email: archis@umn.edu

Research

My field of study is Operations Research. More specifically, my work focuses on theory, models, and algorithms for optimization under uncertainty. I like to study problems that call for analytical techniques from real and functional analysis; convex optimization; statistics; control; and applied probability. I enjoy working closely with undergraduate and graduate students. Upon graduation, my PhD students become faculty or work in finance, consulting, service operations, or tech companies. Some examples of my research work are listed below.

Journal papers

1. Z. Ghatrani and A. Ghate, Percentile optimization in multi-armed bandit problems, forthcoming, Annals of Operations Research, 2024

2. V. Diaz and A. Ghate, Information directed policy sampling for episodic Bayesian Markov decision processes, forthcoming, IISE Transactions, 2024

3. Z. Ghatrani and A. Ghate, Inverse optimization in semi-definite programs to impute unknown constraint matrices, forthcoming, Computers and Operations Research, 2024

4. S. Ramani and A. Ghate, A family of s-rectangular robust MDPs: relative conservativeness, asymptotic analyses, and finite-sample properties, SIAM Journal on Optimization, 34(2), 1540-1568, 2024

5. A. Ghate, Dual ascent and primal-dual algorithms for infinite-horizon nonstationary Markov decision processes, SIAM Journal on Optimization, 33 (3), 1391-1415, 2023

6. Z. Ghatrani and A. Ghate, Inverse Markov decision processes with unknown transition probabilities, IISE Transactions, 55(6), 588-601, 2023

7. S. Ramani and A. Ghate, Robust Markov decision processes with data-driven, distance-based ambiguity sets, SIAM Journal on Optimization, 32(2), 989-1017, 2022

8. A. Ghate, C. Ryan, and R. L. Smith, A Simplex method for countably infinite linear programs, SIAM Journal on Optimization, 31(4), 3157-3183, 2021

9. A. Ghate, Inverse conic linear programs in Banach spaces, Optimization Letters, 15, 289-310, 2021

10. A. Ghate, Imputing radiobiological parameters of the linear-quadratic dose-response model from a radiotherapy fractionation plan, 65(22), 225009, Physics in Medicine & Biology, 2020

11. A. Ghate, Inverse optimization in semi-infinite linear programs, Operations Research Letters, 48(3), 278-285, 2020

12. A. Ghate, Robust continuous linear programs, Optimization Letters, 14, 1627-1642, 2020

13. A. Ajdari, F. Saberian, and A. Ghate, A theoretical framework for learning tumor dose-response uncertainty in individualized spatiobiologically integrated radiotherapy, INFORMS Journal on Computing, 32(4), 930-951, 2020

14. S. Nourollahi and A. Ghate, Inverse optimization in minimum cost flow problems on countably infinite networks, Networks, 73(3), 292-305, 2019

15. S. Nourollahi, A. Ghate, and M Kim, Optimal modality selection in external beam radiotherapy, Mathematical Medicine and Biology, 36(3), 361-380, 2019

16. A. Ajdari, A. Ghate, and M. Kim, Adaptive treatment-length optimization in spatiobiologically integrated radiotherapy, Physics in Medicine and Biology, 63(7), 2018

17. J. Kotas and A. Ghate, Bayesian learning of dose-response parameters from a cohort under response-guided dosing, European Journal of Operational Research, 265(1), 328-343, 2018

18. A. Ghate, Duality in countably infinite monotropic programs, SIAM Journal on Optimization, 27(3), 2010-2033, 2017

19. M. Salemi Parizi, Y. Gocgun, and A. Ghate, Approximate policy iteration for dynamic resource-constrained project scheduling, Operations Research Letters, 45(5), 442-447, 2017

20. S. Nourollahi and A. Ghate, Duality in convex minimum cost flow problems on infinite networks and hypernetworks, Networks, 70(2), 98-115, 2017

21. F. Saberian, A. Ghate, and M. Kim, Spatiotemporally optimal fractionation in radiotherapy, INFORMS Journal on Computing, 29(3), 422-437, 2017

22. F. Saberian, A. Ghate, and M. Kim, A theoretical stochastic control framework for adapting radiotherapy to hypoxia, Physics in Medicine and Biology, 61(19), 7136, 2016

23. A. Ajdari and A. Ghate, Robust spatiotemporally integrated fractionation in radiotherapy, Operations Research Letters, 44(4), 544-549, 2016

24. S. Sinha and A. Ghate, Policy iteration for robust nonstationary Markov decision processes, Optimization Letters, 10(8), 1613-1628, 2016

25. J. Kotas and A. Ghate, Response-guided dosing for rheumatoid arthritis, IIE Transactions on Healthcare Systems Engineering, 6(1), 1-21, 2016

26. S. Sinha, J. Kotas, and A. Ghate, Robust response-guided dosing, Operations Research Letters, 44(3), 394-399, 2016

27. A. Ghate, Robust optimization in countably infinite linear programs, Optimization Letters, 10(4), 847-863, 2016

28. F. Saberian, A. Ghate, and M. Kim, Optimal fractionation in radiotherapy with multiple normal tissues, Mathematical Medicine and Biology, 33(2), 211-252, 2016

29. A. Ghate, Circumventing the Slater conundrum in countably infinite linear programs, European Journal of Operational Research, 246(3), 708-720, 2015

30. F. Saberian, A. Ghate, and M. Kim, A two-variable linear program solves the standard linear-quadratic formulation of the fractionation problem in cancer radiotherapy, Operational Research Letters, 43(3), 254-258, 2015

31. A. Ghate, Optimal minimum bids and inventory scrapping in sequential, single-unit, Vickrey auctions with demand learning, European Journal of Operational Research, 245(2), 555-570, 2015

32. A. Ghate, Inverse optimization in countably infinite linear programs, Operations Research Letters, 43, 231-235, 2015

33. M. Salemi Parizi and A. Ghate, Multi-class, multi-resource advance scheduling with no-shows, cancellations, and overbooking, Computers and Operations Research, 67, 90-101, 2016

34. T D Lortz, I S Dolinskaya, A Ghate, and R L Smith, Solvability in infinite horizon optimization, Operations Research Letters, 43, 498-503, 2015

35. A. Ghate, Shih-Fen Cheng, S. Baumert, D. Reaume, D. Sharma, and R. L. Smith, Sampled fictitious play for multi-action stochastic dynamic programs, IIE Transactions, 46 (7), 742-756, 2014

36. A. Ghate, and R. L. Smith, A linear programming approach to nonstationary infinite horizon Markov decision processes, Operations Research, 61 (2), 413-425, 2013

37. Y. Gocgun, and A. Ghate, Lagrangian relaxation and constraint generation for allocation and advanced scheduling, Computers and Operations Research, 39 (10), 2323-2336, 2012

38. M. Kim, A. Ghate and M. Phillips, A stochastic control formalism for dynamic biologically conformal radiation therapy, European Journal of Operational Research, 219 (3), 541-556, 2012

39. X. Chen, A. Ghate, and A. Tripathi, Dynamic lot-sizing in sequential online retail auctions, European Journal of Operational Research, 215 (1), 257-267, 2011

40. Y. Gocgun, B. Bresnahan, A. Ghate, and M. Gunn, A Markov decision process approach to multi-category patient scheduling in a diagnostic facility, Artificial Intelligence in Medicine, 53 (2), 73-81, 2011

41. M. Epelman, A. Ghate, and R. L. Smith, Sampled fictitious play for approximate dynamic programming, Computers and Operations Research, 38, 1705-1718, 2011

42. A. Ghate, D. Sharma, and R. L. Smith, A shadow simplex method for infinite linear programs, Operations Research, 58 (4), 865-877, 2010

43. W. Wang, A. Ghate, and Z. B. Zabinsky, Adaptive parameterized improving hit-and-run for global optimization, Optimization Methods and Software, 24(4-5), 569-594, 2009

44. M. Kim, A. Ghate, and M. Phillips, A Markov decision process approach to temporal modulation of dose fractions in radiation therapy planning, Physics in Medicine and Biology, 54(14), 4455-4476, 2009

45. A. Ghate, and R. L. Smith, Optimal backlogging over an infinite horizon under time-varying convex production and inventory costs, Manufacturing and Service Operations Management, 11, 362-268, 2009

46. S. Baumert, A. Ghate, S. Kiatsupaibul, Y. Shen, R. L. Smith, and Z. B. Zabinsky, Discrete hit-and-run for sampling points from arbitrary distributions over subsets of integer hyper-rectangles, Operations Research, 57 (3), 727-739, 2009

47. A. Ghate, and R. L. Smith, Characterizing extreme points as basic feasible solutions in infinite linear programs, Operations Research Letters, 37(1), 7-10, 2009

48. A. Ghate, and R. L. Smith, A hit-and-run approach for generating scale invariant Small World networks, Networks, 53 (1), 67-78, 2009

49. A. Ghate, Decentralized search on spheres using small-world Markov chains: expected hitting times and structural properties, Advances in Applied Probability, 4 (4), 966-978, 2008

50. A. Ghate, and R. L. Smith, A dynamic programming approach to efficient sampling from Boltzmann distributions, Operations Research Letters, 36 (6), 665-668, 2008

51. A. Ghate, and R. L. Smith, Adaptive search with stochastic acceptance probabilities for global optimization, Operations Research Letters, 36(3), 285-290, 2008

Peer reviewed conference proceedings

1. M. Salemi Parizi and A. Ghate, Weakly coupled Markov decision processes with imperfect information, Proceedings of the Winter Simulation Conference, National Harbor, MD, 2019

2. S. Nourollahi, A. Ghate, and M. Kim, Robust modality selection in radiotherapy, Proceedings of the INFORMS International Conference on Service Science, 2018, Phoenix, AZ, 2018

3. P. Kumar and A. Ghate, Information Directed Policy Sampling for Partially Observable Markov Decision Processes with parametric uncertainty, Proceedings of the INFORMS International Conference on Service Science, 2018, Phoenix, AZ, 2018

4. M. Salemi Parizi and A. Ghate, Lot-sizing in sequential auctions while learning demand and bid distributions, Proceedings of the Winter Simulation Conference, Washington, D. C., 2016

5. A. Ajdari and A. Ghate, A model predictive control approach for discovering nonstationary fluence-maps in cancer radiotherapy fractionation, Proceedings of the Winter Simulation Conference, Washington, D. C., 2016

6.  Z. B. Zabinsky, W. Wang, Y. Prasetio, A. Ghate, and J. W. Yen, Adaptive probabilistic branch and bound for level set approximation, Proceedings of the Winter Simulation Conference, Phoenix, AZ, 2011

7. Y. Gocgun and A. Ghate, A Lagrangian approach to dynamic resource allocation, Proceedings of the Winter Simulation Conference, Baltimore, MD, 2010

Research monograph

Optimal fractionation in radiotherapy