TY - JOUR N2 - The main aim of this article is to survey and discuss the existing state of art concerning the assignability by a feedback of numerical characteristics of linear continuous and discrete time-varying systems. Most of the results present necessary or sufficient conditions for different formulation of the Lyapunov spectrum assignability problem. These conditions are expressed in terms of various controllability types and optimalizability of the controlled systems and certain properties of the free system such as: regularity, diagonalizability, boundness away, integral separation and reducibility. L1 - http://www.journals.pan.pl/Content/114315/PDF/03_1007-1022_01291_Bpast.No.67-6_13.01.20_K1_TeX.pdf L2 - http://www.journals.pan.pl/Content/114315 PY - 2019 IS - No. 6 EP - 1022 DO - 10.24425/bpasts.2019.130890 KW - assignability KW - controllability KW - Lyapunov spectrum KW - linear time-varying systems A1 - Babiarz, A. A1 - Czornik, A. A1 - Klamka, J. VL - 67 DA - 31.12.2019 T1 - Assignability of numerical characteristics of time-varying systems SP - 107 UR - http://www.journals.pan.pl/dlibra/publication/edition/114315 T2 - Bulletin of the Polish Academy of Sciences Technical Sciences ER -