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Engel Subalgebra
In mathematics, an Engel subalgebra of a Lie algebra with respect to some element ''x'' is the subalgebra of elements annihilated by some power of ad ''x''. Engel subalgebras are named after Friedrich Engel. For finite-dimensional Lie algebras over infinite fields the minimal Engel subalgebras are the Cartan subalgebras. See also *Engel's theorem In representation theory, a branch of mathematics, Engel's theorem states that a finite-dimensional Lie algebra \mathfrak g is a nilpotent Lie algebra_if_and_only_if_for_each_X_\in_\mathfrak_g,_the_adjoint_representation_of_a_Lie_algebra.html" "ti ... References * {{algebra-stub Lie algebras ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lie Algebra
In mathematics, a Lie algebra (pronounced ) is a vector space \mathfrak g together with an Binary operation, operation called the Lie bracket, an Alternating multilinear map, alternating bilinear map \mathfrak g \times \mathfrak g \rightarrow \mathfrak g, that satisfies the Jacobi identity. The Lie bracket of two vectors x and y is denoted [x,y]. The vector space \mathfrak g together with this operation is a non-associative algebra, meaning that the Lie bracket is not necessarily associative property, associative. Lie algebras are closely related to Lie groups, which are group (mathematics), groups that are also smooth manifolds: any Lie group gives rise to a Lie algebra, which is its tangent space at the identity. Conversely, to any finite-dimensional Lie algebra over real or complex numbers, there is a corresponding connected space, connected Lie group unique up to finite coverings (Lie's third theorem). This Lie group–Lie algebra correspondence, correspondence allows one ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friedrich Engel (mathematician)
Friedrich Engel (26 December 1861 – 29 September 1941) was a German mathematician. Engel was born in Lugau, Saxony, as the son of a Lutheran pastor. He attended the Universities of both Leipzig and Berlin, before receiving his doctorate from Leipzig in 1883. Engel studied under Felix Klein at Leipzig, and collaborated with Sophus Lie for much of his life. He worked at Leipzig (1885–1904), Greifswald (1904–1913), and Giessen (1913–1931). He died in Giessen. Engel was the co-author, with Sophus Lie, of the three volume work ''Theorie der Transformationsgruppen'' (publ. 1888–1893; tr., "Theory of transformation groups"). Engel was the editor of the collected works of Sophus Lie with six volumes published between 1922 and 1937; the seventh and final volume was prepared for publication but appeared almost twenty years after Engel's death. He was also the editor of the collected works of Hermann Grassmann. Engel translated the works of Nikolai Lobachevski from Russian i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cartan Subalgebra
In mathematics, a Cartan subalgebra, often abbreviated as CSA, is a nilpotent subalgebra \mathfrak of a Lie algebra \mathfrak that is self-normalising (if ,Y\in \mathfrak for all X \in \mathfrak, then Y \in \mathfrak). They were introduced by Élie Cartan in his doctoral thesis. It controls the representation theory of a semi-simple Lie algebra \mathfrak over a field of characteristic 0 . In a finite-dimensional semisimple Lie algebra over an algebraically closed field of characteristic zero (e.g., a Cartan subalgebra is the same thing as a maximal abelian subalgebra consisting of elements ''x'' such that the adjoint endomorphism \operatorname(x) : \mathfrak \to \mathfrak is semisimple (i.e., diagonalizable). Sometimes this characterization is simply taken as the definition of a Cartan subalgebra.pg 231 In general, a subalgebra is called toral if it consists of semisimple elements. Over an algebraically closed field, a toral subalgebra is automatically abelian. Thus, over ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engel's Theorem
In representation theory, a branch of mathematics, Engel's theorem states that a finite-dimensional Lie algebra \mathfrak g is a nilpotent Lie algebra_if_and_only_if_for_each_X_\in_\mathfrak_g,_the_adjoint_representation_of_a_Lie_algebra.html" "title="mathfrak,\mathfrak ... if and only if for each X \in \mathfrak g, the adjoint representation of a Lie algebra">adjoint map :\operatorname(X)\colon \mathfrak \to \mathfrak, given by \operatorname(X)(Y) = [X, Y], is a nilpotent endomorphism on \mathfrak; i.e., \operatorname(X)^k = 0 for some ''k''. It is a consequence of the theorem, also called Engel's theorem, which says that if a Lie algebra of matrices consists of nilpotent matrices, then the matrices can all be simultaneously brought to a strictly upper triangular form. Note that if we merely have a Lie algebra of matrices which is nilpotent ''as a Lie algebra'', then this conclusion does ''not'' follow (i.e. the naïve replacement in Lie's theorem of "solvable" with "nilpotent", ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |