Oh yeah, I remember E2=E... used it plenty today!
So, let me try to get things straight: R(I - E) is the collectiong of all projections normal to the plane P (like the one in the example you gave)?
Well... maybe the thing is that I don't fully understand what I-E is, as a matter of fact.
One of the things I remember is that ker(E)={0}, the null vector. Or is it just for linear spaces?
Hi!
Studying the introductory chapters of a Operator Theory book, I have found that the author seem to find a lot of demonstrations "easy" and not worthy of demonstrations. Yet, I don't have such ease as he has... For instance, one that has bugged me (on several books) is the proof that...