Back to Range Space and Null Space

Exercise 27

Avg difficulty 3.0

Show that the range spaces and null spaces of powers of linear maps t ⁣:V→Vt\colon V\to V form descending

V⊇R(t)⊇R(t2)⊇…V\supseteq\mathscr{R}(t)\supseteq\mathscr{R}(t^{2})\supseteq\ldots

and ascending

{0⃗}⊆N(t)⊆N(t2)⊆…\text{$\{\hskip 1.00006pt\vec{0}\hskip 1.00006pt\}$}\subseteq\mathscr{N}(t)\subseteq\mathscr{N}(t^{2})\subseteq\ldots

chains. Also show that if kk is such that R(tk)=R(tk+1)\mathscr{R}(t^{k})=\mathscr{R}(t^{k+1}) then all following range spaces are equal: R(tk)=R(tk+1)=R(tk+2)… \mathscr{R}(t^{k})=\mathscr{R}(t^{k+1})=\mathscr{R}(t^{k+2})\ldots\,. Similarly, if N(tk)=N(tk+1)\mathscr{N}(t^{k})=\mathscr{N}(t^{k+1}) then N(tk)=N(tk+1)=N(tk+2)=… \mathscr{N}(t^{k})=\mathscr{N}(t^{k+1})=\mathscr{N}(t^{k+2})=\ldots\,.

Hefferon, Linear Algebra, Maps Between Spaces, Range Space and Null Space, Exercise 27

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Adapted from Linear Algebra © 2016 Jim Hefferon. Licensed under CC BY-SA 3.0 US. Source: Linear Algebra. Imported at revision df2262e.