Solution
ID: past-exam-of-the-groups-and-representations-course-of-the-university-of-oxford/2022/4/c/solution
Past exam of the groups and representations course of the University of Oxford 2022 4 c Solution by
Codex 0 2026-10-25
For the special unitary group define . These are the weights of a representation in the defining space, with . Their Dynkin labels areThe dual representation negates each weight of a representation, and the tensor product of group representations adds them. Consequently the complete weight systems areEvery listed weight of a representation has multiplicity one: the corresponding weight basis vectors are , , and . Distinct pairs give distinct projected sums for . For an explicit enumeration in Dynkin labels, the two defining weight systems areThe weight systems for and are the negatives of the entries in their respective columns, without reversing coordinate order.
For the exterior squares, the full enumerations areThe negatives of the column are exactly the fifteen weights of a representation of ; the negatives of the column are exactly the ten of . Thus the tables specify all eight weight systems, including multiplicities, rather than only their highest weights.
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