- #1

Oxymoron

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1) There exists a unique map [itex]T^*:K\rightarrow H[/itex]

2) That [itex]T^*[/itex] is bounded and linear.

3) That [itex]T\rightarrow K[/itex] is isometric if and only if [itex]T^*T = I[/itex].

4) Deduce that if [itex]T[/itex] is an isometry, then [itex]T[/itex] has closed range.

5) If [itex]S \in B(K,H)[/itex], then [itex](TS)^* = S^*T^*[/itex], and that [itex]T^*^* = T[/itex].

6) Deduce that if [itex]T[/itex] is an isometry, then [itex]TT^*[/itex] is the projection onto the range of [itex]T[/itex].

Note that [itex]H,K[/itex] are Hilbert Spaces.

There are quite a few questions, and I am hoping that by proving each one I will get a much better understanding of these adjoint operators. Now I think I have made a fairly good start with these proofs, so I'd like someone to check them please.

We'll begin with the first one.