Root datum: Difference between revisions

Revision as of 12:20, 13 January 2007

Revision as of 12:22, 13 January 2007

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The elements of <math>\Psi</math> are called the '''roots''' of the root datum, and the elements of <math> \Psi^{\vee} </math> are called the '''coroots'''.

If &Delta;<math> \Psi </math> does not contain <math>2& \alpha;</math> for any &<math>\alpha;</math> in &Delta;<math> \Psi </math> then the root datum is called '''reduced'''.

==The root datum of an algebraic group==