Research
“Research is what I’m doing when I don’t know what I’m doing.” -Wernher Von Braun
At present, I work on various nonlocal PDEs using its underlying probabilistic structure. I also have interest in stochastic control.
Mixed local-nonlocal operators: maximum principles, eigenvalue problems and their applications, (w/ Mitesh Modasiya), accepted in Journal d'Analysis Math.
Nonlocal ergodic control problem in Rd, (w/ Erwin Topp) appeared online in Math. Annalen
Ergodic risk-sensitive control--a survey (w/ Vivek S. Borkar) Annual Reviews in Control, Vol. 55, 118--141, 2023
Existence-Uniqueness for nonlinear integro-differential equations with drift in Rd, (w/ Saibal Khan) SIAM J. of Mathematical Analysis, Vol. 55, 2023 (There is a glitch in the statement of Theorem 5.1 in the published version. For all \gamma should be read as for some \gamma. The correct statement appears in the latest arXived version)
On the monotonicity property of the generalized eigenvalue for weakly-coupled cooperative elliptic system, (w/ Ari Arapostathis, Somnath Pradhan) Journal of Differential Equations, Vol 351, 156–193, 2023
Generalized principal eigenvalues on Rd of second order elliptic operators with rough nonlocal kernel, (w/ Ari Arapostathis, Prasun Roychowdhury) Nonlinear Differential Equations and Applications 30, No. 10, 2023
Boundary regularity of mixed local-nonlocal operators and its application, (w/ Mitesh Modasiya, Abhrojyoti Sen) Annali di Matematica Pura ed Applicata 202, 679-710, 2023
Harnack inequality and principal eigentheory for general infinity Laplacian operators with gradient in RN and applications (w/ Hoang-Hung Vo) CVPDE 61, Article number: 122 (2022)
Ergodic Risk-Sensitive Control of Markov Processes on Countable State Space Revisited, (w/ Somnath Pradhan) ESAIM COCV 28 (2022)
On ergodic control problem for viscous Hamilton-Jacobi equations for weakly coupled elliptic systems, (w/ Ari Arapostathis and Prasun Roychowdhury) Journal of Differential Equations, Vol 314, 25 March 2022, Pages 128-160
Risk-sensitive control for a class of diffusions with jumps, (w/ Ari Arapostathis) Annals of Applied Probability, Vol 32, No. 6, 4106-4142, 2022
Liouville theorems for infinity Laplacian with gradient and KPP type equation (w/ Hoang-Hung Vo) Annali della Scuola Normale Superiore di Pisa, Classe di Scienze, Vol. XXIV, 2023, 1223-1256
A study of nonlocal spatially heterogeneous logistic equation with harvesting, (w/ Mitesh Modasiya) Nonlinear Analysis, Volume 214, January 2022, 112599
A strong maximum principle and a compact support principle for infinity Laplacian, (in honor of Louis Nirenberg) Pure and Applied Functional Analysis, Vol. 8, no. 1, 103--115, 2023
Hopf's lemma for viscosity solutions to a class of non-local equations with applications, (w/ József Lörinczi) Nonlinear Analysis, Vol 204, 2021, 112194
Generalized principal eigenvalues of convex nonlinear elliptic operators in RN (w/ Prasun Roychowdhury) Advances in Calculus of Variations, Vol. 15, No. 4 , 673--691, 2022.
Regularity results of nonlinear perturbed stable-like operators (w/ Mitesh Modasiya) Differential and Integral Equations, Vol 33, 597--624, 2020
A variational characterization of the risk-sensitive average reward for controlled diffusions on Rd, (w/ Ari Arapostathis, Vivek Borkar and Suresh Kumar) SIAM Journal of Control and Optimization, Vol. 58(6), 3785–-3813, 2020
On the policy improvement algorithm for ergodic risk-sensitive control, (w/ Ari Arapostathis, Somnath Pradhan) Proceedings of the Royal Society of Edinburgh Section A: Mathematics, Vol 151, 1305–1330, 2021
Ambrosetti-Prodi type results for Dirichlet problems of the fractional Laplacian-like operators, (w/ József Lörinczi) Integral Equations and Operator Theory 92, 2020.
Integral representation using Green function for fractional Hardy equations (w/ Mousomi Bhakta, Debdip Ganguly, Luigi Montoro), Journal of Differential Equations, 269(7), 2020, 5573-5594
Faber-Krahn type inequalities and uniqueness of positive solutions on metric measure spaces, (w/ Janna Lierl) Journal of Functional Analysis 278, 2020
Principal eigenvalues of a class of nonlinear integro-differential operators, Journal of Differential Equations 268(9), 5257-5282, 2020
A variational formula for risk-sensitive control of diffusion in Rd, (w/ Ari Arapostathis) SIAM J. Control and Optimization 58(1), 85--103, 2020
On overdetermined problems for a general class of nonlocal operators (w/ Sven Jarohs) Journal of Differential Equations, Volume 268, Issue 5, 2368--2393, 2020
On uniqueness of solutions to viscous HJB equations with a subquadratic nonlinearity in the gradient (w/ Ari Arapostathis, Luis Caffarelli) Communications in Partial Differential Equations, 44:12, 1466-1480, 2019
Existence and non-existence results for a class of semilinear nonlocal operators with exterior condition, Pure and Applied Functional Analysis, Vol 6, 2021, 289-308 (Special issue in memory of Professor Felix E. Browder)
Maximum principles and Aleksandrov-Bakelman-Pucci type estimates for non-local Schrödinger equations with exterior conditions, (w/ József Lörinczi) SIAM J. of Math Analysis, 51(3), 1543–1581, 2019
Liouville type results for systems of equations involving fractional Laplacian in exterior domains, Nonlinearity 32, 2246–2268, 2019
Universal constraints on the location of extrema of eigenfunctions of non-local Schrödinger operators, (w/ József Lörinczi) J of Diff Equations, 267 , 267-306, 2019
Maximum principles for time-fractional Cauchy problems with spatially non-local components, (w/ József Lörinczi) Fractional Calculus and Applied Analysis, Vol 21 (5), 1335--1359, 2018
Certain Liouville properties of eigenfunctions of elliptic operators, (w/ Ari Arapostathis and Debdip Ganguly) Transactions of the AMS, Vol. 371(6), 4377--4409, 2019. (The Arxiv version has an improved lower-bound on the decay of non-negative supersolutions. See Corollary ~4.1)
Strict monotonicity of principal eigenvalues of elliptic operators in Rd and risk-sensitive control, (w/ Ari Arapostathis and Subhamay Saha) Journal de Mathématiques Pures et Appliquées, Vol 124, 169-219, 2019.
Zero-sum stochastic differential game with risk-sensitive cost, (w/ Subhamay Saha) Applied Mathematics and Optimization, 81, 113–140, 2020
Controlled equilibrium selection in stochastically perturbed dynamics, (w/ Ari Arapostathis and Vivek Borkar) Annals of Probability, Vol. 46, No. 5, 2749-2799, 2018
Law of large numbers for the many-server earliest-deadline-first queue, (w/ Rami Atar, Haya Kaspi) Stochastic Processes and their Applications, Vol 128 (7), 2270-2296, 2018.
Infinite horizon risk sensitive control of diffusions without any blanket stability assumptions, (w/ Ari Arapostathis) Stochastic Processes and their Applications, Vol 128(5), 1485-1524, 2018.
A Skorokhod map on measure-valued paths with applications to priority queues, (w/ Rami Atar, Haya Kaspi and Kavita Ramanan) Annals of Applied Probability, Vol. 28 (1), 418--481, 2018.
Location of maximizers of eigenfunctions of fractional Schrödinger's equation, Mathematical Physics, Analysis and Geometry 20, no. 4, pages 14, 2017.
An ergodic control problem for many-server multi-class queueing systems with cross-trained servers, Stochastic Systems 7, no. 2, 263-288, 2017.
On viscosity solution of HJB equations with state constraints and reflection control, (w/ Hitoshi Ishii, Subhamay Saha and Lin Wang) SIAM J. of Control and Optimization, Vol. 55, No. 1, 365-396, 2017.
On solutions of mean field games with ergodic cost, (w/ Ari Arapostathis, Johnson Carroll) Journal de Mathématiques Pures et Appliquées 107, 205-251, 2017.
The Dirichlet problem for stable-like Operators and related probabilistic representations, (w/ Ari Arapostathis and Luis Caffarelli) Communications in PDE, Vol. 41 , No. 9, 1472-1511, 2016. (The arxived paper has a different title and contains more detailed proofs)
On scaling limits of power law Shot-noise fields, (w/ François Baccelli) Stochastic Models, Vol 31, No. 2, 187-207, 2015.
Ergodic control of multi-class M/M/N+M queues in the Halfin-Whitt regime, (w/ Ari Arapostathis and Guodong Pang) Annals of Applied Probability, Vol. 25, No. 6, 3511--3570, 2015.
Fluid limits of G/G/1+G queues under non-preemptive Earliest-Deadline-First discipline, (w/ Rami Atar and Haya Kaspi) Maths. of Operation Research, Vol. 40, Issue 3, 683--702, 2015.
Risk-sensitive control for multi-class many server queues in the moderate deviation regime, Maths. of Operation Research, Vol. 39, No. 3, 908-929, 2014.
Control of the multiclass G/G/1 queue in the moderate deviation regime, (w/ Rami Atar) Annals of Applied Probability, Vol. 24, No. 5, 2033-2069, 2014.
Exit time and invariant measure asymptotics for small noise constrained diffusions, (w/ Amarjit Budhiraja) Stochastic Processes and their Applications 121, no. 5, 899–924, 2011.
Risk-sensitive control of diffusions with small running cost, Applied Mathematics and Optimization, Vol. 64, No. 1, 1–12, 2011.
An eigenvalue approach to the risk sensitive control problem in near monotone case, Systems and Control Letters 60, 181-184, 2011.
On a controlled eigenvalue problem, (w/ Vivek S. Borkar) Systems and Control Letters 59, 734–735, 2010.
Small noise asymptotics for invariant densities for a class of diffusions : a control theoretic view, (w/ Vivek S. Borkar) Journal of Math. Analysis and Applications 360. No. 2, 476–484, 2009.(Erratum Arxiv)
Others
Fluid limits of many-server queues with state dependent service rates.
Mean field games with ergodic cost for discrete time Markov processes, (The hypotheses work well for discrete state space Markov chains but do not seem to be satisfied by a good class of Markov chains with continuous state space. At least I don't have any nice family of examples.)
Validity of large deviation principle for stochastic conservation laws.