In this paper, we develop a discrete-time counterpart of a gene regulatory network with three discrete delays which remains fully consistent with its continuous-time counterpart. We begin by showing that standard discretization methods can lead to inconsistencies with the delay parameters $ \tau_i \to 0, \; i = 1, 2, 3 $. In order to address this, the proposed construction is based on a suitable transformation combined with a nearly exact discretization scheme, which is specifically designed to construct a consistent discrete-time model. This approach overcomes the limitations inherent in existing discretization methods for systems involving time delays. We investigate fundamental properties of the obtained discrete system, including positivity of solutions, consistency in the zero-delay limit case, and the occurrence of Neimark–Sacker (NS) bifurcation. For comparison, the same model is discretized using the Euler method, demonstrating that it fails to preserve essential dynamical features of the original delayed system. Numerical simulations are presented to support the theoretical findings and to illustrate the advantages of the proposed discretization framework.
Citation: A. M. A. Abo-Bakr, Mohamed Biomy. A consistent discrete-time counterpart of a gene regulatory network with three time delays[J]. AIMS Mathematics, 2026, 11(10): 34946-34962. doi: 10.3934/math.20261360
In this paper, we develop a discrete-time counterpart of a gene regulatory network with three discrete delays which remains fully consistent with its continuous-time counterpart. We begin by showing that standard discretization methods can lead to inconsistencies with the delay parameters $ \tau_i \to 0, \; i = 1, 2, 3 $. In order to address this, the proposed construction is based on a suitable transformation combined with a nearly exact discretization scheme, which is specifically designed to construct a consistent discrete-time model. This approach overcomes the limitations inherent in existing discretization methods for systems involving time delays. We investigate fundamental properties of the obtained discrete system, including positivity of solutions, consistency in the zero-delay limit case, and the occurrence of Neimark–Sacker (NS) bifurcation. For comparison, the same model is discretized using the Euler method, demonstrating that it fails to preserve essential dynamical features of the original delayed system. Numerical simulations are presented to support the theoretical findings and to illustrate the advantages of the proposed discretization framework.
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