Is there an atlas of Algebraic Groups and corresponding Coordinate rings?

Solution 1:

You probably mean for $G$ to be a reductive group. Keep in mind that $G/B$ is equal to $\text{Proj}(R)$ for many different $R$'s, corresponding to different embeddings of $G/B$ into projective space. The best object to study is the homogeneous coordinate ring (also known as the Cox ring) of $G/B$. In that case, when $G = SL_n$, the homogeneous coordinate ring is in Miller and Sturmfels' Combinatorial Commutative Algebra Chapter 14. For the general case, some keywords to look for are "standard monomial theory", "straightening laws", and "Littelmann path model". The homogeneous coordinate ring of a general $G/B$ (or at least $G/P$ for $P$ a maximal parabolic) might be in Lakshmibai and Raghavan's Standard Monomial Theory: Invariant Theoretic Approach, but I am not sure. Regardless, that is a good introduction to the subject and should have a fairly comprehensive list of references for further information.