2.II.15C

Linear Mathematics | Part IB, 2001

Define the dual V∗V^{*} of a vector space VV. Given a basis {v1,…,vn}\left\{v_{1}, \ldots, v_{n}\right\} of VV define its dual and show it is a basis of V∗V^{*}. For a linear transformation α:V→W\alpha: V \rightarrow W define the dual α∗:W∗→V∗\alpha^{*}: W^{*} \rightarrow V^{*}.

Explain (with proof) how the matrix representing α:V→W\alpha: V \rightarrow W with respect to given bases of VV and WW relates to the matrix representing α∗:W∗→V∗\alpha^{*}: W^{*} \rightarrow V^{*} with respect to the corresponding dual bases of V∗V^{*} and W∗W^{*}.

Prove that α\alpha and α∗\alpha^{*} have the same rank.

Suppose that α\alpha is an invertible endomorphism. Prove that (α∗)−1=(α−1)∗\left(\alpha^{*}\right)^{-1}=\left(\alpha^{-1}\right)^{*}.

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