Commit 2024-04-20 13:53 28c79ff6

feat: define the coroots of a semisimple Lie algebra (#10893) We define the coroots of a finite-dimensional semisimple Lie algebra with coefficients in a field characteristic zero and establish the key property that a coroot is complementary to the kernel of the root. In addition we carry out some related, light refactoring. The most important points are:

• Promote LieModule.weight from a subtype to a structure LieModule.Weight + expand its API (we need this expanded API for the headline results).
• Replace the definition LieAlgebra.rootSpaceProductNegSelf with its range which we call LieAlgebra.corootSpace (in all places where we used this definition, it was the range that we actually used).
• Drop the very old (unused) definitions LieAlgebra.IsRoot and LieModule.IsWeight.