Abstract
We introduce the notions of quasi-invariant and strongly invariant subspaces of a one-parameter family of linear operators acting on a finite-dimensional vector space. The geometric meaning of these notions is that the restrictions of all operators of the family to a quasiinvariant subspace coincide and that the restrictions to a strongly invariant subspace are, in addition, an endomorphism of that subspace. These notions are used to reduce the well-known problem on Ω-periodic solutions of an ω-periodic linear differential system with incommensurable Ω and ω to the algebraic problem on the eigenvalues and eigenvectors of some matrix constructed from the right-hand side of the system.
Similar content being viewed by others
References
Massera, J.L., Observaciones sobre las soluciones periodicas de ecuaciones diferenciales, Bul. de la Facultad de Ing., 1950, vol. 4, no. 1, pp. 37–45.
Kurzweil, J. and Vejvoda, O., Über periodische und fastperiodische Lösungen eines Systems gewöhnlicher Differentialgleichungen, Czech. Math. J., 1955, vol. 5, no. 3, pp. 362–370.
Erugin, N.P., Lineinye sistemy obyknovennykh differentsial’nykh uravnenii s periodicheskimi i kvaziperiodicheskimi koeffitsientami (Linear Systems of Ordinary Differential Equations with Periodic and Quasiperiodic Coefficients), Minsk: Akad. Nauk BSSR, 1963.
Pliss, V.A., Nelokal’nye problemy teorii kolebanii (Nonlocal Problems of Oscillation Theory), Moscow; Leningrad: Nauka, 1964.
Gaishun, I.V., Lineinye uravneniya v polnykh differentsialakh (Linear Total Differential Equations), Minsk: Navuka i Tekhnika, 1989.
Grudo, E.I., Periodic solutions with incommensurable periods of periodic differential systems, Differ. Equations, 1986, vol. 22, no. 9, pp. 1036–1041.
Grudo, E.I. and Demenchuk, A.K., Periodic solutions with incommensurable periods of periodic nonhomogeneous linear differential systems, Differ. Equations, 1987, vol. 23, no. 3, pp. 284–289.
Demenchuk, A.K., On periodic solutions of Pfaffian systems, Izv. Akad. Nauk BSSR. Ser. Fiz.-Mat., 1988, no. 4, pp. 18–25.
Il’in, Yu.A., On periodic systems that have a solution with incommensurable period, Differ. Uravn. i Protsessy Upravl., 2010, no. 4, pp. 134–144.
Vinberg, E.B., Kurs algebry (A Course of Algebra), Moscow: Factorial, 1999.
Nemytskii V.V. and Stepanov V.V., Kachestvennaya teoriya differentsial’nykh uravnenii (Qualitative Theory of Differential Equations), Moscow: Gos. Izd. Tekh. Teor. Lit., 1947.
Borukhov V.T., Controlled invariant flags in the state spaces of linear autonomous finite-dimensional dynamical systems, Differ. Equations, 1995, vol. 31, no. 1, pp. 5–11.
Author information
Authors and Affiliations
Corresponding author
Additional information
Original Russian Text © V.T. Borukhov, 2018, published in Differentsial’nye Uravneniya, 2018, Vol. 54, No. 5, pp. 585–591.
Rights and permissions
About this article
Cite this article
Borukhov, V.T. Strongly Invariant Subspaces of Nonautonomous Linear Periodic Systems and Solutions Whose Period Is Incommensurable with the Period of the System Itself. Diff Equat 54, 578–585 (2018). https://doi.org/10.1134/S0012266118050026
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1134/S0012266118050026