Can you rephrase the question? What is e ?

[pattiecake]

Can you rephrase the question? What is "e"?

Is {A e Mn,n | AB = BA for a fixed B e Mn,n a subspace of Mn,n? (where Mn,n is a matrix M, of dimension n by n)? Not having had a logic class, I have /no idea/ what this is asking...

I'm not even sure what the e is. Its a small capital e - looks like a greek letter. Equivalent to?

 

[AKG]

It is this symbol : \in. A \in M_{n,n} means that A is in the space of (n x n)-matrices. So, is the set S_B of all (n x n)-matrices that commute with B a subspace of M_{n,n}? You should know of 3 things to test for to determine if it's a subspace (the subspace test) and using the basic axioms of matrix multiplication, you should be able to solve the problem. The symbol \in is a set theoretic one that says that something is an element of a set. It's not really a logic symbol, it's one used in mathematics all the time. Seeing as how you're working with vector spaces, I'm surprised you've never seen it.

 

[Data]

Yes. Read x \in y as "x is in y" or "x is an element of the set y."

Some other useful symbols are \exists and \forall. Read \exists as "there exists", and \forall as "for any," or "for all."

These symbols are fairly ubiquitous in mathematics (as are many, many others).

 

[pattiecake]

I'm retArdEd. Thanks!