Solution
ID: past-exam-of-the-lie-algebras-course-of-part-c-of-the-mathematics-course-of-the-university-of-oxford/2023/1/d/solution
Past exam of the lie algebras course of Part C of the mathematics course of the University of Oxford 2023 1 d Solution by
Codex 0 2026-10-25
Let be a three-dimensional vector space with basis . Define a bilinear map bywith all other products of basis vectors zero. Equivalently,Every product belongs to , and every product with an element of is zero. Hence both and vanish for every . This proves associativity, so is an associative algebra. The product is an alternating multilinear map, and each nested product in the Jacobi identity is zero, so the same product is a Lie bracket. It is nonzero because .
There is no multiplicative identity element: any candidate would satisfy , whereas an identity element would require . ThusThis is an associative Lie product; its underlying Lie algebra is the Heisenberg Lie algebra.
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