Essays on the structure of reductive groups From root datum to reductive group
نویسنده
چکیده
A root datum is a quadruple L = (L,∆, L,∆) in which (1) L is a free Z-module of finite rank and L is its dual Hom(L,Z); (2) ∆ is a finite subset of L and ∆ is one of L; (3) implicit is a map α 7→ α from ∆ to∆ such that (〈α, β∨〉) is a Cartan matrix. In the literature, this is usually called a based root datum. For my purposes it serves as a better beginning. I’ll say later something about the distinction.
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Essays on the structure of reductive groups Root systems
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