We propose a mathematical formalism for discrete multi-scale dynamical systems induced by maps which parallels the established geometric singular perturbation theory for continuous-time fast-slow systems. We identify limiting maps corresponding to both 'fast' and 'slow' iteration under the map. A notion of normal hyperbolicity is defined by a spectral gap requirement for the multipliers of the fast limiting map along a critical fixed-point manifold $ S $. We provide a set of Fenichel-like perturbation theorems by reformulating pre-existing results so that they apply near compact, normally hyperbolic submanifolds of $ S $. The persistence of the critical manifold $ S $, local stable/unstable manifolds $ W^{s/u}_{loc}(S) $ and foliations of $ W^{s/u}_{loc}(S) $ by stable/unstable fibers is described in detail. The practical utility of the resulting discrete geometric singular perturbation theory (DGSPT) is demonstrated in applications. First, we use DGSPT to identify singular geometry corresponding to excitability, relaxation, chaotic and non-chaotic bursting in a map-based neural model. Second, we derive results which relate the geometry and dynamics of fast-slow ODEs with non-trivial time-scale separation and their Euler-discretized counterpart. Finally, we show that fast-slow ODE systems with fast rotation give rise to fast-slow Poincaré maps, the geometry and dynamics of which can be described in detail using DGSPT.
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Figure 1. Examples of normally hyperbolic critical manifolds $ S $ in dimension $ n = 3 $. In (a)-(d) $ \dim S = 2 $ and there exists a single non-trivial multiplier $ |\mu| \neq 1 $. There are four generic possibilities depending on $ \mu $: (a) attracting and orientation preserving; (b) attracting and orientation reversing; (c) repelling and orientation preserving; (d) repelling and orientation reversing. In (e)-(f) $ S $ is saddle-type with $ \dim S = 1 $ and two non-trivial multipliers $ |\mu_a| < 1 $ and $ |\mu_r| > 1 $. Two of four generic possibilities are shown: (e) orientation preserving along stable/unstable fibers $ w^{s/u}_{loc}(z) $; (f) orientation reversing along $ w^s_{loc}(z) $
Figure 2. Stable/unstable manifolds $ W^{s/u}_{loc}(S_n) $ associated to a normally hyperbolic critical manifold $ S_n $ are foliated by lower dimensional stable/unstable manifolds $ w^{s/u}_{loc}(z) $ associated to base points $ z \in S_n $. The case of a $ 1- $dimensional saddle-type critical manifold in dimension $ n = 3 $ is shown here ($ S_n $ is shown in green). In this case the manifolds $ W^{s/u}_{loc}(S_n) $ (shown in blue/red) are $ 2- $dimensional and foliated by the $ 1- $dimensional stable/unstable manifolds $ w^{s/u}_{loc}(z) $ associated to base points $ z \in S_n $. Representative stable/unstable fibers $ w^{s/u}(z_i) $ with base points $ z_i \in S_n $ for $ i = 1, 2 $ are also shown
Figure 3. Action of the oblique projection operator $ \Pi^{S_n}_{\mathcal N} $ along $ \mathcal N $ onto $ TS_n $ in the case of a $ 1- $dimensional attracting critical manifold $ S_n $ (green). The splitting (18) implies that the leading order perturbation $ G(z, 0) $ at each point $ z \in S_n $ can be decomposed into components in the tangent bundle $ T_z S_n $, and the (transverse) linear fast fiber $ \mathcal N_z $ tangent to the nonlinear fast fiber $ w^s_{loc}(z) $ shown in blue in the figure. The component in $ T_zS_n $ is given by $ \Pi_{\mathcal N}^{S_n}G(z, 0) \in T_zS_n $, and sufficient to determine the reduced map (24), see also Proposition 2.16
Figure 4. Reduced and $ m $'th iterate maps on $ S_{n, \varepsilon} $ defined in equations (24) and (26) respectively. The normally hyperbolic critical manifold and the corresponding perturbed slow manifold are shown again in green and shaded green respectively. The dynamics of the map (10) within $ S_{n, \varepsilon} $ are governed to leading order in $ \varepsilon $ by the reduced map (24). Iterates are generically separated by distances of $ O( \varepsilon) $, as shown in (a). Iterates of the $ m $'th iterate reduced map (26) shown in (b) can be separated by $ O(1) $ distances if the number of iterates $ m $ is comparable to $ \varepsilon^{-1} $. For both reduced and $ m $'th iterate maps, non-trivial dynamics is only possible for $ 0 < \varepsilon \ll 1 $. See however Remark 2.22, which describes a possible approach to identifying non-trivial dynamics on $ S $ for $ \varepsilon = 0 $ in the dual limit $ ( \varepsilon, m) \to (0, \infty) $
Figure 5. Fast-slow maps in the standard form (30) can be characterised geometrically as the subclass of fast-slow maps in general form (10) for which the fast foliation has been or can be globally rectified. Such a situation is sketched in (a). In (b) we show an example of a fast-slow map with an isolated fixed point $ Q $. Such a map cannot be written in standard form (30) since the fast foliation cannot be globally rectified
Figure 6. A normally hyperbolic critical manifold $ S $ for the map (36) perturbs to an $ O( \varepsilon)- $close locally invariant slow manifold $ S_ \varepsilon $ for $ 0 < \varepsilon \ll 1 $. This is described in Theorem 3.1. Dynamics within $ S_ \varepsilon $ are governed by the map (21), i.e. approximated to leading order in $ \varepsilon $ by the reduced map (24). Several iterates $ \bar z_ \varepsilon, \bar z_ \varepsilon^2, \ldots , \bar z_ \varepsilon^6 \in S_ \varepsilon $ starting from a point $ z_ \varepsilon \in S_ \varepsilon $ are shown for illustrative purposes. Theorem 3.3 provides further details for the case in which $ S $ is has a graph representation $ y = \varphi_0(x) $, in which case $ S_ \varepsilon $ can be calculated up to $ O( \varepsilon^2) $ using the formula (38)
Figure 7. The stable/unstable manifolds $ W^{u/s}_{loc}(S) $ (here in shaded blue/red) of a normally hyperbolic critical manifold $ S $ (shaded green) perturb to $ O( \varepsilon)- $close positively/negatively invariant manifolds $ W^{s/u}_{loc}(S_ \varepsilon) $ (blue/red) which intersect along the slow manifold $ S_ \varepsilon $ (green), see Theorem 3.4
Figure 8. Positive invariance of the perturbed stable fibers $ \{w_{loc}^s(z_ \varepsilon)\}_{z_ \varepsilon \in S_ \varepsilon} $ of a $ 1- $dimensional critical manifold in dimension $ n = 2 $. By the invariance property in Theorem 3.5 (i), initial conditions $ q_1, q_2 $ in the stable fiber $ w^s_{loc}(z_{ \varepsilon, 1}) $ with base point $ z_{ \varepsilon, 1} \in S_ \varepsilon $ are mapped by $ H $ into the stable fiber $ w^s_{loc}(z_{ \varepsilon, 2}) $, then $ w^s_{loc}(z_{ \varepsilon, 3}) $, with base points $ z_{ \varepsilon, 2} $ and $ z_{ \varepsilon, 3} $ corresponding to iterates of $ z_{ \varepsilon, 1} $. Moreover, iterates are exponentially contracted towards their base points on $ S_ \varepsilon $ by Theorem 3.5 (iii). In (a): the orientation preserving case in which $ S $ has a non-trivial multiplier $ \mu \in (0, 1) $. In (b): the orientation reversing case with $ \mu \in (-1, 0) $
Figure 9. Geometry and dynamics of the fast-slow Chialvo map (77) in the singular limit $ \varepsilon = 0 $, with parameter values $ \tilde a = 1 $, $ \tilde b = 5 $, $ \tilde c = 3.5 $ and $ k = 0.035 $. The critical manifold $ S $ has a cubic-like profile, with normally hyperbolic and attracting (repelling) critical manifolds $ S^a_{\pm} $ ($ S^r_{\pm} $) shown in blue (red) separated by non-hyperbolic fold points $ F_\pm $ (orange) and a supercritical flip point $ Q $ (green); see Lemma 5.4. Iterates of the layer map (79) along vertical fast fibers (shaded grey) are sketched along with the direction of iteration, in order to illustrate the fast dynamics. The reduced map, i.e. (82) truncated at $ O( \varepsilon^2) $, has a unique unstable fixed point $ p_\ast \in S_-^r $, see Proposition 5.10. The direction of 'slow iteration' under the reduced map is indicated with single arrows. Also shown in cyan is the (numerically computed) curve of period-2 points $ S^2 $ bifurcating from the flip point $ Q $, as well as numerically identified flip bifurcations $ Q_{\pm}^2 $ in the second iterate map $ v \mapsto \bar v^2 $. A period-doubling route to chaos occurs with increasing $ w $; see [71] and Remark 5.6
Figure 10. Global dynamics of the fast-slow Chialvo map (77) for $ 0 < \varepsilon \ll 1 $. Singular structure for $ \varepsilon = 0 $ including critical manifolds $ S_{\pm}^a $, $ S_{\pm}^r $, the fold, flip and equilibrium points $ F_{\pm} $, $ Q $ and $ p_\ast $ respectively are shown overlaid with numerically computed iterates of (77) with initial condition $ (w, v) = (1/4, 2) $, $ \varepsilon = 10^{-3} $, $ \tilde a = 1 $, $ \tilde b = 5 $ and varying values of $ \tilde c, k $. The 'slow nullcline' $ \{g(w, v, 0) = 0\} $ is also shown in shaded grey. Dynamics away from the non-normally hyperbolic points $ F_\pm $ and $ Q $ is described by the theory in Sections 2 and 3. We identify four distinct behaviours depending on $ (\tilde c, k) $, which are described in the text. (a) Case I: Excitability, with $ (\tilde c, k) = (7, 0.07) $. (b) Case II: Relaxation, with $ (\tilde c, k) = (3.5, 0.07) $. (c) Case III: Non-chaotic bursting, with $ (\tilde c, k) = (3.5, 0.035) $. (d) Case IV: Chaotic bursting, with $ (\tilde c, k) = (3.5, 0.02) $
Figure 11. Setup for $ \varepsilon = 0 $. The layer problem (99) has a manifold of hyperbolic limit cycles $ \mathcal M $, shown here in shaded purple, which contains the limit cycle $ \Gamma_{\alpha_\ast} $ and extends over the open $ \alpha- $interval $ V_\alpha \ni \alpha_\ast $. A Poincaré map $ P_\Delta : \Delta \to \Delta $ on the cross-section $ \Delta $ shown in shaded green is induced by the flow of the layer problem (99). Hyperbolicity of the limit cycles $ \Gamma_\alpha $ implies that the 1-dimensional submanifold $ S_\Delta = \mathcal M \cap \Delta $ (bold green) is a normally hyperbolic critical manifold for $ P_\Delta $, see Lemma 5.22
Figure 12. Perturbation of the singular geometry and dynamics for $ \varepsilon = 0 $ (left) for $ 0 < \varepsilon \ll 1 $ (right). We sketch the 3-dimensional case of a normally hyperbolic and attracting limit cycle manifold $ \mathcal M $. Theorem 5.23 describes the persistence properties for the Poincaré map $ P_{\Delta} $ on an arbitrary cross-section $ \Delta $. Three representative stable fibers on $ \Delta $ for $ \varepsilon = 0 $ are shown in blue on the left, which perturb to invariant stable fibers for $ 0 < \varepsilon \ll 1 $ (also in blue) on the right, e.g. $ w_{loc}^s(z) $ perturbs to $ w_{loc}^s(z_ \varepsilon) $. A number of example iterates are shown on $ \Delta $ for both $ \varepsilon = 0 $ and $ 0 < \varepsilon \ll 1 $. Note that the arrows connecting points on e.g. $ w_{loc}^s(z_ \varepsilon) $ and $ w_{loc}^s({\bar z_ \varepsilon}^5) $ only show the direction of iteration (they do not indicate a single iteration). The persistence of the manifold of limit cycles $ \mathcal M $ as a nearby locally invariant 'slow manifold' $ \mathcal M_ \varepsilon $ as described by Theorem 5.23 is also shown ($ \mathcal M_ \varepsilon $ is shown in a darker shade of purple)
[1] | O. D. Anosova, On invariant manifolds in singularly perturbed systems, J. Dynam. Control Systems, 5 (1999), 501-507. doi: 10.1023/A:1021739205527. |
[2] | O. D. Anosova, Invariant manifolds in singularly perturbed systems, Tr. Mat. Inst. Steklovaa, 236 (2002), 27-32. |
[3] | L. Arcidiacono, M. Engel and C. Kuehn, Discretized fast-slow systems near pitchfork singularities, J. Difference Equ. Appl., 25 (2019), 1024-1051. doi: 10.1080/10236198.2019.1647185. |
[4] | C. Baesens, Slow sweep through a period-doubling cascade: Delayed bifurcations and renormalisation, Physica D: Nonlinear Phenomena, 53 (1991), 319-375. doi: 10.1016/0167-2789(91)90068-K. |
[5] | E. Benoit, Dynamic Bifurcations: Proceedings of a Conference Held in Luminy, France, March 5-10, 1990, Lecture Notes in Mathematics, 1493. Springer-Verlag, Berlin, 1991. doi: 10.1007/BFb0085019. |
[6] | P. Carter and B. Sandstede, Unpeeling a homoclinic banana in the Fitzhugh-Nagumo system, SIAM J. Appl. Dyn. Syst., 17 (2018), 236-349. doi: 10.1137/16M1080707. |
[7] | D. R. Chialvo, Generic excitable dynamics on a two-dimensional map, Chaos, Solitons & Fractals, 5 (1995), 461-479. doi: 10.1016/0960-0779(93)E0056-H. |
[8] | M. Courbage, V. I. Nekorkin and L. V. Vdovin, Chaotic oscillations in a map-based model of neural activity, Chaos: An Interdisciplinary Journal of Nonlinear Science, 17 (2007), 043109, 13 pp. doi: 10.1063/1.2795435. |
[9] | P. De Maesschalck, T. S. Doan and J. Wynen, Intrinsic determination of the criticality of a slow–fast Hopf bifurcation, Journal of Dynamics and Differential Equations, 33 (2021), 2253-2269. doi: 10.1007/s10884-020-09903-x. |
[10] | P. De Maesschalck, F. Dumortier and R. Roussarie, Canard Cycles, vol. 73, Springer, 2021. |
[11] | P. De Maesschalck and M. Wechselberger, Neural excitability and singular bifurcations, J. Math. Neurosci., 5 (2015), Art. 16, 32 pp. doi: 10.1186/s13408-015-0029-2. |
[12] | Y. Do and J. M. Lopez, Slow passage through multiple bifurcation points, Discrete Contin. Dyn. Syst. Ser. B, 18 (2013), 95-107. doi: 10.3934/dcdsb.2013.18.95. |
[13] | F. Dumortier and R. Roussarie, Canard cycles and center manifolds, Mem. Amer. Math. Soc., 121 (1996), x+100 pp. doi: 10.1090/memo/0577. |
[14] | M. Engel and H. Jardón-Kojakhmetov, Extended and symmetric loss of stability for canards in planar fast-slow maps, SIAM J. Appl. Dyn. Syst., 19 (2020), 2530-2566. doi: 10.1137/20M1313611. |
[15] | M. Engel and C. Kuehn, Discretized fast-slow systems near transcritical singularities, Nonlinearity, 32 (2019), 2365-2391. doi: 10.1088/1361-6544/ab15c1. |
[16] | M. Engel, C. Kuehn, M. Petrera and Y. Suris, Discretized fast-slow systems with canards in two dimensions, SIAM J. Appl. Dyn. Syst., 32 (2022), Paper No. 19, 41 pp. doi: 10.1007/s00332-021-09778-2. |
[17] | N. Fenichel, Asymptotic stability with rate conditions, Indiana University Mathematics Journal, 23 (1974), 1109-1137. doi: 10.1512/iumj.1974.23.23090. |
[18] | N. Fenichel, Asymptotic stability with rate conditions, II, Indiana University Mathematics Journal, 26 (1977), 81-93. doi: 10.1512/iumj.1977.26.26006. |
[19] | N. Fenichel, Geometric singular perturbation theory for ordinary differential equations, Journal of Differential Equations, 31 (1979), 53-98. doi: 10.1016/0022-0396(79)90152-9. |
[20] | N. Fenichel and J. Moser, Persistence and smoothness of invariant manifolds for flows, Indiana University Mathematics Journal, 21 (1971/72), 193-226. doi: 10.1512/iumj.1972.21.21017. |
[21] | A. Fruchard and R. Schäfke, A survey of some results on overstability and bifurcation delay, Discrete Contin. Dyn. Syst. Ser. S, 2 (2009), 931-965. doi: 10.3934/dcdss.2009.2.931. |
[22] | A. Goeke and S. Walcher, A constructive approach to quasi-steady state reductions, Journal of Mathematical Chemistry, 52 (2014), 2596-2626. doi: 10.1007/s10910-014-0402-5. |
[23] | J. Guckenheimer, Towards a global theory of singularly perturbed dynamical systems, Nonlinear Dynamical Systems and Chaos, Progr. Nonlinear Differential Equations Appl., Birkhäuser, Basel, 19 (1996), 213-225. |
[24] | J. Guckenheimer and P. Holmes, Nonlinear Oscillations, Dynamical Systems, and Bifurcation of Vector Fields, Applied Mathematical Sciences, 42. Springer-Verlag, New York, 1983. doi: 10.1007/978-1-4612-1140-2. |
[25] | M. G. Hayes, T. J. Kaper, P. Szmolyan and M. Wechselberger, Geometric desingularization of degenerate singularities in the presence of fast rotation: A new proof of known results for slow passage through Hopf bifurcations, Indagationes Mathematicae, 27 (2016), 1184-1203. doi: 10.1016/j.indag.2015.11.005. |
[26] | M. W. Hirsch, C. C. Pugh and M. Shub, Invariant manifolds, Bulletin of the American Mathematical Society, 76 (1970), 1015-1019. doi: 10.1090/S0002-9904-1970-12537-X. |
[27] | A. Huber and P. Szmolyan, Geometric singular perturbation analysis of the Yamada model, SIAM Journal on Applied Dynamical Systems, 4 (2005), 607-648. doi: 10.1137/040604820. |
[28] | B. Ibarz, J. M. Casado and M. A. Sanjuán, Map-based models in neuronal dynamics, Physics Reports, 501 (2011), 1-74. doi: 10.1016/j.physrep.2010.12.003. |
[29] | E. M. Izhikevich, Simple model of spiking neurons, IEEE Transactions on Neural Networks, 14 (2003), 1569-1572. doi: 10.1109/TNN.2003.820440. |
[30] | E. M. Izhikevich and F. Hoppensteadt, Classification of bursting mappings, International Journal of Bifurcation and Chaos, 14 (2004), 3847-3854. doi: 10.1142/S0218127404011739. |
[31] | H. Jardón-Kojakhmetov and C. Kuehn, A survey on the blow-up method for fast-slow systems, Mexican Mathematicians in the World—Trends and Recent Contributions, Contemp. Math., Amer. Math. Soc., RI, 775 (2021), 115-160, arXiv: 1901.01402. doi: 10.1090/conm/775/15591. |
[32] | H. Jardón-Kojakhmetov, J. M. Scherpen and D. del Puerto-Flores, Stabilization of a class of slow–fast control systems at non-hyperbolic points, Automatica J. IFAC, 99 (2019), 13-21. doi: 10.1016/j.automatica.2018.10.008. |
[33] | S. Jelbart, N. Pages, V. Kirk, J. Sneyd and M. Wechselberger, Process-oriented geometric singular perturbation theory and calcium dynamics, SIAM Journal on Applied Dynamical Systems, 21 (2022), 982-1029. doi: 10.1137/21M1412402. |
[34] | S. Jelbart and M. Wechselberger, Two-stroke relaxation oscillators, Nonlinearity, 33 (2020), 2364-2408. doi: 10.1088/1361-6544/ab6a77. |
[35] | Z. Jing, J. Yang and W. Feng, Bifurcation and chaos in neural excitable system, Chaos Solitons Fractals, 27 (2006), 197-215. doi: 10.1016/j.chaos.2005.04.060. |
[36] | C. K. R. T. Jones, Geometric singular perturbation theory, Dynamical Systems, Lecture Notes in Math., Springer, Berlin, 1609 (1995), 44-118. doi: 10.1007/BFb0095239. |
[37] | P. I. Kaleda, Singular systems on the plane and in space, Journal of Mathematical Sciences, 179 (2011), 475-490. doi: 10.1007/s10958-011-0605-2. |
[38] | T. J. Kaper, Systems theory for singular perturbation problems, Analyzing Multiscale Phenomena Using Singular Perturbation Methods: American Mathematical Society Short Course, Baltimore, Maryland, 56 (1999), 85. |
[39] | I. Kosiuk and P. Szmolyan, Geometric singular perturbation analysis of an Autocatalator model, Discrete and Continuous Dynamical Systems, 2 (2009), 783-806. doi: 10.3934/dcdss.2009.2.783. |
[40] | I. Kosiuk and P. Szmolyan, Scaling in singular perturbation problems: Blowing up a relaxation oscillator, SIAM Journal on Applied Dynamical Systems, 10 (2011), 1307-1343. doi: 10.1137/100814470. |
[41] | I. Kosiuk and P. Szmolyan, Geometric analysis of the Goldbeter minimal model for the embryonic cell cycle, Journal of Mathematical Biology, 72 (2016), 1337-1368. doi: 10.1007/s00285-015-0905-0. |
[42] | N. Kruff and S. Walcher, Coordinate-independent singular perturbation reduction for systems with three time scales, Mathematical Biosciences and Engineering, 16 (2019), 5062-5091. doi: 10.3934/mbe.2019255. |
[43] | M. Krupa and P. Szmolyan, Extending geometric singular perturbation theory to nonhyperbolic points-fold and canard points in two dimensions, SIAM Journal on Mathematical Analysis, 33 (2001), 286-314. doi: 10.1137/S0036141099360919. |
[44] | C. Kuehn, Multiple Time Scale Dynamics, Applied Mathematical Sciences, 191. Springer, Cham, 2015. doi: 10.1007/978-3-319-12316-5. |
[45] | C. Kuehn, N. Berglund, C. Bick, M. Engel, T. Hurth, A. Iuorio and C. Soresina, A general view on double limits in differential equations, Physica D: Nonlinear Phenomena, 431 (2022), 133105, 26 pp. doi: 10.1016/j.physd.2021.133105. |
[46] | C. Kuehn and P. Szmolyan, Multiscale geometry of the Olsen model and non-classical relaxation oscillations, Journal of Nonlinear Science, 25 (2015), 583-629. doi: 10.1007/s00332-015-9235-z. |
[47] | Y. A. Kuznetsov, Elements of Applied Bifurcation Theory, Third edition, Applied Mathematical Sciences, 112. Springer-Verlag, New York, 2004. doi: 10.1007/978-1-4757-3978-7. |
[48] | Y. A. Kuznetsov and H. G. E. Meijer, Numerical Bifurcation Analysis of Maps. From Theory to Software, Cambridge Monographs on Applied and Computational Mathematics, 34. Cambridge University Press, Cambridge, 2019. doi: 10.1017/9781108585804. |
[49] | I. Lizarraga, R. Marangell and M. Wechselberger, Slow unfoldings of contact singularities in singularly perturbed systems beyond the standard form, Journal of Nonlinear Science, 30 (2020), 3161-3198. doi: 10.1007/s00332-020-09647-4. |
[50] | I. Lizarraga, B. Rink and M. Wechselberger, Multiple time-scales and the parametrisation method in geometric singular perturbation theory, Nonlinearity, 34 (2021), 4163-4201. doi: 10.1088/1361-6544/ac04bf. |
[51] | I. Lizarraga and M. Wechselberger, Computational singular perturbation method for nonstandard slow-fast systems, SIAM Journal on Applied Dynamical Systems, 19 (2020), 994-1028. doi: 10.1137/19M1242677. |
[52] | S. S. Muni, H. O. Fatoyinbo and I. Ghosh, Dynamical effects of electromagnetic flux on Chialvo neuron map: Nodal and network behaviors, International Journal of Bifurcation and Chaos, 32 (2022), 2230020, 26 pp. doi: 10.1142/S0218127422300208. |
[53] | V. Nekorkin and L. Vdovin, Diskretnaya model neyronnoy aktivnosti, Izvest Vys Ucheb Zaved Prikladnaya Nelinejnaya Dinamika, 15 (2007), 36-60. |
[54] | K. Nipp and D. Stoffer, Attractive Invariant Manifolds for Maps: Existence, Smoothness and Continuous Dependence on the Map, no. 92, 11 in Research Report / Eidgenössische Technische Hochschule Zürich, Seminar für Angewandte Mathematik, ETH, Zürich, 1992. |
[55] | K. Nipp and D. Stoffer, Invariant manifolds and global error estimates of numerical integration schemes applied to stiff systems of singular perturbation type-part I: Rk-methods, Numerische Mathematik, 70 (1995), 245-257. doi: 10.1007/s002110050118. |
[56] | K. Nipp and D. Stoffer, Invariant manifolds and global error estimates of numerical integration schemes applied to stiff systems of singular perturbation type–part II: Linear multistep methods, Numerische Mathematik, 74 (1996), 305-323. doi: 10.1007/s002110050218. |
[57] | K. Nipp and D. Stoffer, Invariant Manifolds in Discrete and Continuous Dynamical Systems, EMS Tracts in Mathematics, 21. European Mathematical Society (EMS), Zürich, 2013. doi: 10.4171/124. |
[58] | K. Nipp, D. Stoffer and P. Szmolyan, Graph transform and blow-up in singular perturbations, AIP Conference Proceedings, American Institute of Physics, (2009), 861-868. doi: 10.1063/1.3241616. |
[59] | W. F. Osgood, Lehrbuch der Funktionentheorie, 2nd edition, no. 20, 1 in B. G. Teubners Sammlung von Lehrbüchern auf dem Gebiete der Mathematischen Wissenschaften mit Einschluss ihrer Anwendungen, Teubner, Leipzig, 1912, Literaturangaben. |
[60] | C. Pötzsche, Slow and fast variables in non-autonomous difference equations, Journal of Difference Equations and Applications, 9 (2003), 473-487. doi: 10.1080/1023619031000076542. |
[61] | N. F. Rulkov, Regularization of synchronized chaotic bursts, Physical Review Letters, 86 (2001), 183. doi: 10.1103/PhysRevLett.86.183. |
[62] | N. F. Rulkov, Modeling of spiking-bursting neural behavior using two-dimensional map, Physical Review E, 65 (2002), 041922, 9 pp. doi: 10.1103/PhysRevE.65.041922. |
[63] | J. A. Sanders, F. Verhulst and J. Murdock, Averaging Methods in Nonlinear Dynamical Systems, Second edition, Applied Mathematical Sciences, 59. Springer, New York, 2007. |
[64] | S. Schecter and P. Szmolyan, Persistence of rarefactions under Dafermos regularization: Blow-up and an exchange lemma for gain-of-stability turning points, SIAM Journal on Applied Dynamical Systems, 8 (2009), 822-853. doi: 10.1137/080715305. |
[65] | A. L. Shilnikov and N. F. Rulkov, Subthreshold oscillations in a map-based neuron model, Physics Letters A, 328 (2004), 177-184. doi: 10.1016/j.physleta.2004.05.062. |
[66] | M. Shub, Global Stability of Dynamical Systems, Astérisque, 56. Société Mathématique de France, Paris, 1978. |
[67] | M. Stiefenhofer, Singular perturbation with limit points in the fast dynamics, Zeitschrift für angewandte Mathematik und Physik ZAMP, 49 (1998), 730-758. doi: 10.1007/s000330050118. |
[68] | P. Szmolyan, Transversal heteroclinic and homoclinic orbits in singular perturbation problems, Journal of Differential Equations, 92 (1991), 252-281. doi: 10.1016/0022-0396(91)90049-F. |
[69] | P. Szmolyan and M. Wechselberger, Relaxation oscillations in $\mathbb{R}^3$, Journal of Differential Equations, 200 (2004), 69-104. doi: 10.1016/j.jde.2003.09.010. |
[70] | A. N. Tikhonov, Systems of differential equations containing small parameters in the derivatives, Mat. Sbornik N. S., 73 (1952), 575-586. |
[71] | F. L. Trujillo, J. Signerska-Rynkowska and P. Bartłomiejczyk, Periodic and chaotic dynamics in a map-based neuron model, arXiv preprint, arXiv: 2111.14499. |
[72] | B. van der Pol, A theory of the amplitude of free and forced triode vibrations, Radio Review, 1 (1920), 701-710. |
[73] | B. van der Pol, On "relaxation-oscillations", The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 2 (1926), 978-992. |
[74] | F. Wang and H. Cao, Mode locking and quasiperiodicity in a discrete-time Chialvo neuron model, Communications in Nonlinear Science and Numerical Simulation, 56 (2018), 481-489. doi: 10.1016/j.cnsns.2017.08.027. |
[75] | M. Wechselberger, Geometric Singular Perturbation Theory Beyond the Standard Form, Frontiers in Applied Dynamical Systems: Reviews and Tutorials, 6. Springer, Cham, 2020. doi: 10.1007/978-3-030-36399-4. |
[76] | S. Wiggins, Normally Hyperbolic Invariant Manifolds in Dynamical Systems, Applied Mathematical Sciences, 105. Springer-Verlag, New York, 1994. doi: 10.1007/978-1-4612-4312-0. |
Examples of normally hyperbolic critical manifolds
Stable/unstable manifolds
Action of the oblique projection operator
Reduced and
Fast-slow maps in the standard form (30) can be characterised geometrically as the subclass of fast-slow maps in general form (10) for which the fast foliation has been or can be globally rectified. Such a situation is sketched in (a). In (b) we show an example of a fast-slow map with an isolated fixed point
A normally hyperbolic critical manifold
The stable/unstable manifolds
Positive invariance of the perturbed stable fibers
Geometry and dynamics of the fast-slow Chialvo map (77) in the singular limit
Global dynamics of the fast-slow Chialvo map (77) for
Setup for
Perturbation of the singular geometry and dynamics for