[1] T.S. Angell, A. Kirsch, On the necessary conditions for optimal control of retarded systems, Appl.
Math. Optim. 22 (1990) 117–145.
[2] H.T. Banks, Necessary condition for control problems with variable time lags, SIAM J. Control
Optim. 8 (1968) 9–47.
[3] J.T. Betts, S.L. Campbell, K.C. Thompson, Solving optimal control problems with control delays
using direct transcription, Appl. Numer. Math. 108 (2016) 185–203.
[4] F. Colonius, D. Hinrichsen, Optimal control of functional differential systems, SIAM J. Control
Optim. 16 (1978) 861–879.
[5] T.L. Friesz, Dynamic Optimization and Differential Games, Springer: New York, 2010.
[6] T. Guinn, Reduction of delayed optimal control problems to nondelayed problems, J. Optim. Theory
Appl. 18 (1976) 371–377.
[7] L. Gollmann, D. Kern, H. Maurer, Optimal control problems with delays in state and control vari
ables subject to mixed control-state constraints, Optim. Control Appl. Meth. 30 (2009) 341–365.
[8] L. Gollmann, H. Maurer, Theory and applications of optimal control problems with multiple time
delays, J. Ind. Manag. Optim. 10 (2014) 413.
[9] Z. Gong, C. Liu, K. L. Teo, X. Yi, Optimal control of nonlinear fractional systems with multiple
pantograph-delays, Appl. Math. Comput. 425 (2022) 127094.
[10] A. Halanay, Optimal controls for systems with time lag, SIAM J. Control 6 (1968) 215–234.
[11] S.M. Hoseini, H.R. Marzban, Costate Computation by an Adaptive Pseudospectral Method for
Solving Optimal control problems with piecewise constant Time Lag, J. Optim. Theory Appl. 170
(2016) 735–755.
[12] A. Jajarmi, M. Hajipour, An efficient finite difference method for the time-delay optimal control
problems with time-varying delay, Asian J. Control 19 (2017) 554–563.
[13] A. Jajarmi, M. Hajipour, D. Baleanu, A new approach for the optimal control of time-varying delay
systems with external persistent matched disturbances, J. Vib. Control 24 (2018) 4505–4512, .
[14] C. Liu, R. Loxton, K.L. Teo, S. Wang, Optimal state-delay control in nonlinear dynamic systems Automatica 135 (2022) 109981.
[15] C. Liu, Z. Gong, K.L. Teo, S. Wang, Optimal control of nonlinear fractional-order systems with
multiple time-varying delays, J. Optim. Theory Appl. 193 (2022) 856–876.
[16] S.M. Mirhosseini-Alizamini, S. Effati, A. Heydari, An iterative method for suboptimal control of
linear time-delayed systems, Systems Control Lett. 82 (2015) 40–50
[17] H.R. Marzban, S.M. Hoseini, Optimal control of linear multi-delay systems with piecewise constant
delays, IMA J. Math. Control Inform. 35 (2018) 183–212.
[18] H.R. Marzban, H. Pirmoradian, A direct approach for the solution of nonlinear optimal control
problems with multiple delays subject to mixed state-control constraints, Appl. Math. Model. 53
(2018) 189–213.
[19] H.R. Marzban, H. Pirmoradian, A novel approach for the numerical investigation of optimal control
problems containing multiple delays, Optimal Control Appl. Methods 39 (2018) 302–325.
[20] S.T. Malik, On necessary optimality conditions for singular controls in dynamical systems with a
delay in control, Numer. Funct. Anal. Optim. 39 (2018) 1669–1689.
[21] S.M.Meshkani, S. Effati, A. Heydari, Necessary optimality conditions for optimal control problems
with time-varying delays, J. Adv. Math. Model. 13 (2023) 269–283.
[22] S.M. Mirhosseini-Alizamini, S. Effati, An iterative method for suboptimal control of a class of
nonlinear time-delayed systems, Internat. J. Control 92 (2019) 2869–2885.
[23] S.M. Mirhosseini-Alizamini, Solving linear optimal control problems of the time delayed systems
by Adomian decomposition method, Iranian J. Numer. Anal. Optim. 9 (2019) 165–183.
[24] D. Wu, Y. Bai, Time- scaling transformation for optimal control problem with time- varying delay,
Discrete Contin. Dyn. Syst. Ser. S 13 (2020) 1683–1695
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