1. Extending Rademacher Theorem to Set-Valued Maps. (with A. Daniilidis )
to appear in SIAM J. Optimization
2. Set-Driven Evolution for Multiagent System. (with R. Capuani and A. Marigonda)
J Optim Theory Appl (2023). https://doi.org/10.1007/s10957-023-02344-8
3. Dynamical systems and Hamilton-Jacobi-Bellman equations on the Wasserstein space and their L2 representations (with C. Jimenez and A. Marigonda )
SIAM Journal on Mathematical Analysis Vol. 55, Iss. 5 (2023)
4. Metric Regularity for Set-Valued Maps in Fréchet-Montel Spaces. (with M. Ivanov and N. Zlateva) in Set-Valued Var. Anal 31, 18 (2023). https://doi.org/10.1007/s11228-023-00679-y
5. Compatibility of State Constraints and Dynamics for Multiagent Control Systems (with G. Cavagnari, A. Marigonda ) in Journal of Evolution, 21, 4491-4537 (2021)
6. Strong bi-metric regularity in affine optimal control problems (with A. Corella, V. Veliov ) in Pure and Applied Functional Analysis, vol 6, N. 6, 1119-1137 (2021)
7. Extremal shift rule and viability property for mean field type control systems (with I. Averboukh, A. Marigonda ) in J Optim Theory Appl, 89, 1, 244-270 (2021)
8. Nonsmooth feedback control for multi-agent dynamics (with M. Bivas ) in Set-Valued Var. Anal. 29, 2,501-518 (2021)
9. Characterization of Filippov representable maps and Clarke subdifferentials (with M. Bivas, A. Daniilidis ) in Math. Program. 189, 99–115. (2020)
10. Optimal control for the evolution of deterministic multi-agent systems (with M. Bivas ) in J. Differential Equations 269, Issue 3, pp 2228-2263. (2020)
11. Representation Formulas for Limit Values of Long Run Stochastic Optimal Controls (with R. Buckdahn, Li, J. and Renault J. ) in SIAM Journal on Control and Optimization Vol. 58, No. 4 : pp. 1846-1873 (2020)
12. Optimal Control of Multiagent Systems in the Wasserstein Space (with C. Jimenez and A. Marigonda) in `` Calculus of Variations and PDE' 59, 58. (2020) https://doi.org/10.1007/s00526-020-1718-6
13. On the metric regularity of affine optimal control problems (with T. Scarinci and V. Veliov ) in `` Journal of Convex Analysis , 27, 2, 511-535 (2020)
14. Existence and characterization of the values of two players differential games with state constraints (with P. Bettiol and R. Vinter ) in `` Applied Mathematics & Optimization, 80,3, 765-799 (2019)
15. Viability of open sets for stochastic optimal control (with R. Buckdahn and H. Frankowska ) in `` Stochastic Processes and Applications , 6(1): 129, 10, 4108-4118 (2019)
16. A differential game on Wasserstein space. Application to weak approachability with partial monitoring (with V. Perchet ) in `` Journal of Dynamics & Game, 6(1): 65-85 (2019)
17. Mayer control problem with probabilistic uncertainty on initial positions. (with A. Marigonda) in `` J. Differential Equations 264, no. 5, 3212-3252. (2018)
18. Hamilton Jacobi Isaacs equations for differential games with asymmetric information on probabilistic initial condition. (with C. Jimenez) in `` J. Math. Anal. Appl. 457 , no. 2, 1422-1451. (2018)
19. Second order differential equations with random perturbations and small parameters (with M. Kamenskii and S. Pergamenchtchikov ) in `` Proceedings of the Royal Society of Edinburgh: Section A Mathematics ' no. 4, 763-779. (2017)
20. Differential games with asymmetric information and without Isaacs condition (with R. Buckdahn, C. Rainer and Y. Xu ) in `` International Journal of Game Theory '  N. 4, 795 -816. (2016)
21. Limit Value for Optimal Control with General Means (with X. Li and J. Renault) in `` Discrete and Continuous Dynamical Syst. Serie A '' Vol. 36 N. 4, pp.2113-2132 ( 2016)
22. Differential games with incomplete information on initial positions and without Isaacs condition (with C. Jimenez and Y. Xu ) in `` Dynamic Games and Applications'' Volume 6, Issue 1, pp 82-96 (2016)
23. On a unified framework for approachability with full or partial monitoring (with V. Perchet ) in `` Maths of Operation Research '' 40 (3) 513-541 (2015)
24. On Representation Formulas for Long Run Averaging Optimal Control Problem (with R. Buckdahn and J. Renault) in `` Journal of Differential Equations '' 259, no. 11, 5554-5581 (2015).
25. Vanishing discount limit for nonexpansive optimal control and differential games (with P. Cannarsa ) in `` SIAM Journal of Control and Opti. '' 53 (4), 1789-1814 (2015).
26. Averaging problem for weakly coupled nonexpansive control systems (with H. Sedrakyan ) in `` Nonlinear Analysis TMA '' 113, 147-158 (2015).
27. Metric Regularity and Stability of Optimal Control Problems for Linear Systems (with V. Veliov) in `` SIAM Journal of Control and Opti. '' Vol. 51(5), 4118-4137 (2014)
28. Value in Mixed strategies for Zero-Sum Stochastic Differential Games without Isaacs Condition (with R. Buckdahn and J. Li) in `` Annals of Probability '' Vol. 42 (4), 1724-1768 (2014)
29. Pure and Random strategies in differential game with incomplete informations (with P. Cardaliaguet and C. Jimenez) in `` Journal of Dynamics and games '' Vol. 1 (3), 363-375 (2014)
30. Existence of limit value for stochastic optimal control. (with R. Buckdahn and D. Goreac) in `` Applied Maths and Opti '' Volume 70, Issue 1, pp 1-28 (2014)
31. On sets of occupational measures generated by a deterministic control system on an infinite time horizon (with V. Gaitsgory) in `` Nonlinear Analysis TMA '' Vol. 88, pp 27-41 (2013)
32. On the Small-Time Controllability of Discontinuous Piece-Wise Linear Systems (with M. Krastanov) in `` Systems and Control Letters '' Vol. 62, pp.218-223. (2013)
33. Value function of differential games without Isaacs conditions. An approach with nonanticipative mixed strategies (with R. Buckdahn and J. Li ) in `` Int. Journal of Game Theory '' Volume 42, Issue 4, pp 989-1020 (2013) .
34. On Existence of a limit value in some non expansive optimal control problems (with J. Renault) in `` SIAM Journal of Control and Opti. '' Vol. 49, N.5, pp. 2118-2132 (2012)
35. Holder Metric Regularity of Set-Valued Maps (with H. Frankowska ) in `` Math. Programming Ser.A '' Springer, Vol. 132, N.1 pp. 333-354 (2012)
36. Stochastic optimal control and linear programming approach (with R. Buckdahn and D. Goreac ) in `` Applied Mathematics & Optimization '' Volume 63, Number 2, 257-276 (2011)
37. Optimal Control with Hysteresis Nonlinearity and Multidimensional Play Operator (with A. Gudovich) in `` SIAM Journal of Control and Opti. '' Vol. 49, N.2 pp. 788-807 (2011)
38. Some recent aspects of differential game theory (Survey) (with R. Buckdahn and P. Cardaliaguet )in `` Dynamic Games and Applications'' , Volume 1, Number 1, 74-114 (2011)
39. Lipschitz Continuity and Semiconcavity Properties of the Value Function of a Stochastic Control Problem (with R. Buckdahn and P. Cannarsa) in `` NoDEA : Nonlinear Differential Equations and Applications '' Volume 17, Number 6, 715-728, (2010)
40. The problem of optimal control with reflection studied through a linear optimization problem stated on occupational measures (with O. Serea ) in `` Nonlinear Analysis ''Nonlinear Analysis TMA Volume 72, Issue 6, Pages 2803-2815 (2010)
41. Another proof for the equivalence between invariance of closed sets with respect to stochastic and deterministic systems (with Buckdahn R., Rainer C. and Teichman J. ) in `` Bulletin des Sciences Mathématiques '' Vol 134 pp. 207-214 (2010) (Available online 24 November 2007)
42. Existence of Equilibria of Set-valued Maps on Bounded Epilipschitz Domains in Hilbert Spaces without Invariance Conditions (with A. Goudovitch, M. Kamenskii ) in `` Nonlinear Analysis ''Nonlinear Analysis TMA Volume 72, Issue 1, Pages 262-276 (2010)
43. On limiting values of stochastic differential equations with small noise intensity tending to zero (with Buckdahn R. and Ouknine Y. ) in `` Bulletin des Sciences Mathématiques ''Bull. Sci. math. 133 (2009) 229-237
44. Linear programming analysis of deterministic infinite horizon optimal control problems (discounting and time averaging cases) (with V. Gaitsgory ) in `` SIAM Journal of Control and Opti. '' Vol. 48, 4, pp. 2480-2512 (2009)
45. Existence of periodic solutions of a ordinary differential equation perturbed by a small parameter: An averaging approach (with A. Gudovich and M. Kamenski ) in `` Comptes rendus mathématiques de l'Académie des Sciences, Paris. '' C. R. Acad. Sci. Paris, Ser. I 347 (2009) 369-374
46. Approchability Theory, Discriminating Domain and Differential Games (with As Soulaimani S. and Sorin S. ) in `` SIAM Journal of Control and Opti. '' Vol. 48, No. 4, pp. 2461 - 2479
47. Parameterized minimax problem: on Lipschitz-like dependence of the solution with respect to the parameter (with N. Zlateva ) in `` SIAM J. Optim. '' Vol. 19, N. 3, pp. 1250-1269 (2008)
48. Deterministic differential games under probability knowledge of initial condition (with P. Cardaliaguet ) in ``International Game Theory Review '' Vol. 10, N. 1, 1-16 (2008).
49. Controlled Stochastic Differential Equations under constraints in infinite dimensional spaces (with R. Buckdahn and G. Tessitore ) in `` SIAM Journal of Control and Opti. '' Vol. 47, 1, 218-250 (2008).
50. On the reachability problem for uncertain Hybrid Systems (with Gao Y. and Lygeros J. ) in `` IEEE Transaction on Automatic Control '' Vol. 52, N. 9, 1572-1587 (2007).
51. An Averaging method for singularly perturbed systems with Hysteresis in Infinite Dimensional Spaces (with Goudovitch A., Kamenskii M. Nistri P.)in `` Differential Equations and Dynamical systems'' Vol. 15, N.3-4, pp. 267-294 (2007) .
52. Impulse Differential Inclusions Driven by Discrete Measures (with Lygeros J. and Rzezuchowski T. ) in `` Lecture Notes in Computer Science '' Springer, Vol. 4416/2007, pp. 385-398. (2007).
53. Pursuit Evasion games with impulsive Dynamics (with Cruck E. and Saint-Pierre P.) in Annals of International Society of Dynamic Games, Birkhauser Vol. 9, pp. 223-248, (2007).
54. Zero-sum state constrained differential games: Existence of value for Bolza problem. (with P. Bettiol and P. Cardaliaguet ) in `` International Journal of Game Theory'' Vol. 34, N.4, pp. 495-527. (2006)
55. On Lipschitz Regularity of Minimizers of a Calculus of Variations Problem with non Locally Bounded Lagrangians (with N. Zlateva ) in in `` Comptes rendus Mathématiques,'' Vol. 343, 1, Pages 69-74 (2006).
56. Convergence of neural networks for programming problems via a nonsmooth Lojasiewicz inequality (with M. Forti and P. Nistri)in `` IEEE Transactions on Neural networks '' Vol. 17 , No. 6, pp.1471-1486 (2006).
57. Aubin Criterion for Metric Regularity, (with A. Dontchev and N. Zlateva) in `` Journal of convex Analysis ''Vol. 13 , No. 2, pp 281-297 (2006).
58. The Reachability Problem for Uncertain Hybrid Systems Revisited: A Viability Theory Perspective (with Y. Gao and J. Lygeros ) in `` Lecture Notes in Computer Science, Springer,'' Volume 3927, pp. 242 - 256 (2006)
59. A characterization of approximately controllable linear stochastic differential equation (with R. Buckdahn and G. Tessitore ) in `` Stochastic Partial differential Equations and Applications, G. Da Prato and L. Tubaro Eds '' Series of Lecture Notes in pure and appl. Math., Chapman & Hall Vol.245 , pp. 253-260 (2006)
60. Existence of Equilibria on Epilipschitz sets without invariance conditions (with M. Kamenskii ) in `` Fixed Point Theory and Applications '' Vol.2005 , N. 3, pp. 257-279 (2005)
61. Stochastic control and compatible subsets of contraints (with C. Rainer ) in `` Bulletin des Sciences Mathématiques '' Vol.129, N. 1, pp. 39-55 (2005).
62. Optimal Control of Uncertain Systems with Incomplete Information for the Disturbances, (with V. Veliov ) in `` SIAM J. Control and Optimization '' Vol.43 N. 4. pp.1373-1399 (2005)
63. On the Dynamics of a Differential Inclusion built upon a Nonconvex Constrained Minimization Problem . (with P. Nistri) in `` J. Optimization Theory and Appl. '' Vol. 129, N. 1 pp.39-55. (2005).
64. On attainability of a set by at least one solution to a differential inclusion, (with G. Gabor ) in `` Optimization,'' vol.53, N.5-6 pp.563-582 (2004)
65. On the Control of Uncertain Impulsive Systems: Approximate Stabilization and Controlled Invariance (with Gao, Y. Lygeros J. Seube N.) in `` International Journal of Control '' Vol. 77, N. 16, pp.1393-1407 (2004). .
66. Averaging of Perturbed One-Sided-Lipschitz Differential Inclusions , (with T. Donchev and M. Kamenskii ) in `` Zeitschrift fur Analysis und ihre Anwendungen '' Vol. 23, N. 4, pp 1-10 (2004).
67. A Two-point Boundary Value Problem for a class of Differential Inclusions, (with T. Donchev ) in `` Journal of Convex and Nonlinear Analysis ''Vol. 5, N. 1, pp. 59-70 (2004)
68. Stochastic Control with Exit Time and Constraints, Application to Small Time Attainability of sets (with R. Buckdahn, C. Rainer A. Rascanu) in `` Appl. Math. Optim.'' Vol. 49, 2, pp.99-112. (2004)
69. Generalized Neural Network for Non-Smooth Programming Problems, (with M. Forti and P. Nistri) in `` IEEE Transactions on Circuit and Systems'' Vol. 51, 9, pp.1741-1753. (2004)
70. Averaging method for discontinuous Mayer's problem of singularly perturbed control systems (with F. Wattbled) in `` Nonlinear Analysis: Theory, Methods \& Applications ''Vol. 54, pp. 819-837 (2003) .
71. Approximate stabilisation of uncertain hybrid systems (with Gao, Y. Lygeros J. Seube N.) in `` Proceedings of Computation and control. 6th international workshop, HSCC 2003, Berlin: Springer. Lect. Notes Comput. Sci. '', 2623, pp. 203-215,(2003) .
72. Equilibria and strict equilibria of multivalued maps on noninvariant sets (with G. Gabor and P. Cardaliaguet) in `` Annales Polonici Mathematici, '', vol 82-1, pp.19-37, (2003) .
73. On Nonemptiness of viability kernels for infinite-dimensional differential inclusions (with T. Donchev) in `` Applied Maths Letters. '', Vol. 16, pp 1195-1199 (2003).
74. On Existence of Equilibria of Lipschitz Set-Valued Maps (with G. Gabor) in Bolletino Unione Math. Italian. '', 8, 6-B, pp.309-321 (2003).
75. On Existence of Solutions to Differential Equations or Inclusions Remaining in a Prescribed Closed Subset of a Finite-dimensional Space . (with G. Gabor ) in `` J. Differential Equations '' Vol. 185, No. 2, pp. 483-512 (2002).
76. Singularly perturbed second order differential inclusions by an averaging method. . (with M. Kamenskii, P. Nistri) in `` International Journal of Pure and Applied Mathematics '' vol. 3, N. 3, pp. 343-355 (2002).
77. A representation formula for the mean curvature motion (with R. Buckdahn and P. Cardaliaguet), in ``SIAM J. Math. Anal." Vol. 33, N. 4, pp.827-846.(2002)
78. Oleinik-Lax formulas and multitime Hamilton-Jacobi systems (with S. Plaskacz) in `` Nonlinear Analysis: Theory, Methods \& Applications ''Vol. 51, N. 6 pp. 957-967 (2002) .
79. Optimal control in presence of unobservable uncertainties (with V. Veliov ) in `` Proceedings of Bulgarian Academy of Sciences '' T. 55, N. 8 pp.11-16 (2002).
80. Viability of moving sets for stochastic differential equations (with Buckdahn R. ,Rainer C. , A. Rascanu) in `` Advances in differential Equations '' Vol. 7, N. 9, pp. 1045--1072 (2002).
81. Optimal control of discrete-time uncertain systems with imperfect measurement (with R. Moitié, V. Veliov) in `` IEEE transactions on Automatic Control''Vol. 47, 11, pp. 1909-1914. (2002).
82. On open-loop and feedback attainability of a closed set for nonlinear control systems . (with P. Nistri) in `` J. Math. Anal. Appl '' Vol. 270, No. 2, pp. 474-487, (2002).
83. A Viability Approach for Optimal Control with Infimum Cost, (with O. Serea ) in `` Annals. Stiint. Univ. Al. I. Cuza Iasi,s.I a, Mat, '' t. XLVIII, f.1., p. 113 - 132 (2002).
84. Solutions Tubes for Differential Inclusions within a Collection of sets. (with V. Veliov ) in `` Control and Cybernetics. Vol 31. 3, pp.849-862. '' (2002).
85. Differential games with state-constraints . (with P. Cardaliaguet and P. Saint-Pierre ) in `` Petrosjan, L. A. (ed.) et al., 10th international symposium on dynamic games and applications. St. Petersburg, Russia. In 2 vol. St. Petersburg: International Society of Dynamic Games, St. Petersburg State Univ. '' pp.179-182. (2002)
86. Impulse differential inclusions: A viability approach to hybrid systems (with Aubin J-P. Lygeros J.\ Sastry S. Seube N.) in `` IEEE transactions on Automatic Control'' vol. 47, 1, pp. 2-20, 2002.
87. Representation formulas for Hamilton Jacobi equations related to calculus of variation problems. (with S. Plaskacz) in `` Topological Methods in Nonlinear Analysis, '' vol. 20, pp.85-118, 2002.
88. De l'existence de solutions d'équations différentielles assujetties à rester dans un ensemble fermé. . (with G. Gabor ) in `` Comptes-Rendus de l'Académie des Sciences. S\'erie I. PARIS, vol 333, pp. 913-918 '' (2001).
89. Sliding mode control of uncertain systems: a singular perturbation approach . (with M. Kamenskii, P. Nistri) in `` IMA J. Math. Control, '' 19, 4, pp. 377-398 (2002).
90. Value-functions for differential games and control systems with discontinuous terminal cost. (with S. Plaskacz) in `` SIAM J. Control and Optimization '' Vol. 39, N. 5 (2001),  pp. 1485-1498 1615-1632.
91. Local small time controlability and attainability of a set for nonlinear control system. (with M.Krastanov) in `` ESAIM Control, Opti and Calcul. of Variations, '' Vol. 6, pp. 499-516.(2001)
92. Pursuit differential games with state constraints. (with P. Cardaliaguet and P. Saint-Pierre) in `` SIAM J. Control and Optimization '' Vol. 39, N. 5 (2001),  pp.1615-1632
93. Discontinuous Mayer control problem under state-constraints. (with S. Plaskacz) in `` Topological Methods in Nonlinear Analysis, '' Vol 15, pp. 91-100.(2000).
94. Numerical schemes for discontinuous value functions of optimal control (with P. Cardaliaguet and P. Saint-Pierre) in `` Set-valued Analysis '' Vol. 8, N. 1 & 2 (2000) pp: 111-126.
95. Stochastic Viability For Backward Stochastic Differential Equations and Applications to Partial Differential Equations. (with Buckdahn R. , A. Rascanu) in `` Probability Theory and Relat. fields '' .Vol. 116, pp. 485-504.(2000)
96. Dissipative control systems and disturbance attenuation for nonlinear-H infty control problems. (with H. Frankowska) in `` Appl. Math. Optim.''vol. 40 N. 2 pp 163-181. (1999).
97. Numerical methods for differential games. (with P. Cardaliaguet and P. Saint-Pierre) in `` Stochastic and differential games : Theory and numerical methods '' (1999) pp. 177-247. Annals of the international Society of Dynamic Games, M. Bardi, T.E.S. Raghavan, T. Parthasarathy Eds. Birkhauser.
98. Viability under uncertain initial state (with V. Veliov) in `` Set-valued Analysis ''.ol. 7 No 1, pp. 55-87.1999
99. Singular Perturbations for differential equations and inclusions : an Approach through constrained Systems. in `` Nonlinear Analysis: Theory, Methods \& Applications '' Vol. 32, N.5, pp.697-710.1998.
100. Existence of stochastic control under state constraints. (with Buckdahn R. Peng S., Rainer C. ) in `` Comptes-Rendus de l'Académie des Sciences. Série I.'' PARIS, t. 327, pp. 17-22. (1998).
101. Stabilization of uncertain Control Systems through Piecewise Constant Feedback. . (with S.Seube) in `` J. Math. Anal. Appl '' N. 196 pp.240-255.1998.
102. On a generalization of Tichonoff Theorem to Differential Inclusions . in `` Doklady of Russian Academy of Sciences (in russian) '' V.360, N. 3, 1998, PP.309-312.
103. An Algorithm for Viability Kernels in Holderian Case:Approximation by discrete dynamical systems. (with P. Saint-Pierre) in `` J. Mathematics of Systems, Estimation and Control. Mat.'' Vol, 8,N.1,pp.17-29.1998
104. Multitarget Control Problems. (with L. Doyen) in ``J. Optimization Theory and Applt .'' vol.93, pp.121-140. 1997
105. Propriétés de Viabilité pour des équations différentielles stochastiques rétrogrades et applications à des équations aux dérivées partielles. (with Buckdahn R.,, Rascanu A. ) in `` Comptes-Rendus de l'Académie des Sciences. S\'erie I. PARIS, '' t. 325, pp. 1159-1162.(1997).
106. Optimal times for constrained nonlinear control problems without local controllability. (with P. Cardaliaguet and P. Saint-Pierre) in `` Appl. Math. Opti.'' Vol. 36 (1997) pp: 21-42.
107. Singular perturbations in nonlinear optimal control. (with H. Zhang) in ``Differential and Integral Equations, .'' Vol. 8, N.4,pp.931-944.1995
108. Contribution à l'étude des jeux différentiels quantitatifs et qualitatifs avec contrainte sur l'état. (with P. Cardaliaguet and P. Saint-Pierre), in `` Comptes-Rendus de l'Académie des Sciences. Série I. PARIS, '' t. 321, pp. 1443-1548.(1995).
109. Some Algorithms for Differential Games with two Players and one Target (with P. Cardaliaguet and P. Saint-Pierre), in `` RAIRO Mathematical Modeling and Numerical Analysis '', .Vol 28, N,4.pp. 441-461. (1994)
110. Temps optimaux pour des problèmes de contrôle avec contraintes et sans contrôlabilité locale. (with P. Cardaliaguet and P. Saint-Pierre), in `` Comptes-Rendus de l'Académie des Sciences. Série I. PARIS, '' t. 318, pp.607-612 (1994).
111. Perturbations singulières pour des problèmes de contrôles et des inclusions différentielles. in `` Comptes-Rendus de l'Académie des Sciences. Série I. PARIS, t. 318, pp.607-612'' (1993).
112. Differential inclusions and target problems in `` SIAM J. Control and Optimization '' Vol. 30, No 2, pp.324-335. 1992
113. Enveloppes d'invariance pour des inclusions différentielles Lipschitziennes: Application aux problèmes de cibles. in `` Comptes-Rendus de l'Académie des Sciences. Série I.'' PARIS, t.314, pp.343-347.1992
114. Un algorithme déterminant les noyaux de viabilité pour les inclusions différentielles avec contraintes (with H. Frankowska) in `` Comptes-Rendus de l'Académie des Sciences. Série I. PARIS,'' t. 312, pp. 31-36. 1991
115. Viability kernels of differential inclusions with constraints: Algorithm and applications. (with H. Frankowska) in `` J. Mathematics of Systems, Estimation and Control. Mat.'' vol.1, No 3, pp.371-388.,1991
116. Playable Differential Games . in `` J. Math. Anal. Appl '' vol.1, No 1, pp. 194-211.1991.
117. Frontières de domaines d'invariance et de viabilité pour des inclusions différentielles avec contraintes. in `` Comptes-Rendus de l'Académie des Sciences. Série I. PARIS, t. 311, pp. 904-914. 1991

Preprints or Works in Progress:

1. Hamilton Jacobi characterizations of the Vanishing discount limit for optimal control (with P. Cannarsa, S. Gaubert, C. Mendico )