Classification of semi-simple Lie groups

[metroplex021]

A while ago I heard the following two facts about semi-simple Lie groups (though I have a feeling they may have to be restricted to connected semi-simple Lie groups):

1. That semi-simple Lie groups are classified by their weight (and co-weight) and root (and co-root) lattices;
2. That all of these lattices can be deduced from the fundamental representations of the group. (So that if we have a complete set of representations we can go on and infer the group.)

Can someone confirm for me that these are indeed the case, or suggest a reference where the above are stated? (I am a physics graduate but with little pure math knowledge, so the more approachable the better.) Thanks a lot!

 

[fresh_42]

AFAIK you need only the root systems and the adjoint representations for the classification, not all possible representations. It's a bit easier for the Lie algebras.