Paper 4, Section II, G
Let be a real vector space. What is the dual of If is a basis for , define the dual basis for , and show that it is indeed a basis for .
[No result about dimensions of dual spaces may be assumed.]
For a subspace of , what is the annihilator of ? If is -dimensional, how does the dimension of the annihilator of relate to the dimension of ?
Let be a linear map between finite-dimensional real vector spaces. What is the dual map ? Explain why the rank of is equal to the rank of . Prove that the kernel of is the annihilator of the image of , and also that the image of is the annihilator of the kernel of .
[Results about the matrices representing a map and its dual may be used without proof, provided they are stated clearly.]
Now let be the vector space of all real polynomials, and define elements of by setting to be the coefficient of in (for each ). Do the form a basis for ?