TY - JOUR ID - Grabowski2018 LB - Grabowski2018 AU - Grabowski, Piotr TI - Small-gain theorem for a class of abstract parabolic systems ST - Small-gain theorem for a class of abstract parabolic systems JO - Opuscula Math. JA - Opuscula Math. JF - Opuscula Mathematica PY - 2018 VL - 38 IS - 5 SP - 651 EP - 680 DO - https://doi.org/10.7494/OpMath.2018.38.5.651 UR - https://doi.org/10.7494/OpMath.2018.38.5.651 AB - We consider a class of abstract control system of parabolic type with observation which the state, input and output spaces are Hilbert spaces. The state space operator is assumed to generate a linear exponentially stable analytic semigroup. An observation and control action are allowed to be described by unbounded operators. It is assumed that the observation operator is admissible but the control operator may be not. Such a system is controlled in a feedback loop by a controller with static characteristic being a globally Lipschitz map from the space of outputs into the space of controls. Our main interest is to obtain a perturbation theorem of the small-gain-type which guarantees that null equilibrium of the closed-loop system will be globally asymptotically stable in Lyapunov's sense. KW - control of infinite-dimensional systems KW - semigroups KW - infinite-time LQ-control problem KW - Lur'e feedback systems SN - 1232-9274 ER -