Примеры использования Reductive group на Английском языке и их переводы на Русский язык
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Some authors do not require reductive groups to be connected.
Reductive groups have a rich representation theory in various contexts.
More generally, the roots of a reductive group form a root datum, a slight variation.
A reductive group G over a field k is called quasi-split if it contains a Borel subgroup over k.
Note, however, that complete reducibility fails for reductive groups in positive characteristic apart from tori.
Every reductive group over a field admits a central isogeny from the product of a torus and some simple groups. .
Some examples among the classical groups are: Every nondegenerate quadratic form q over a field k determines a reductive group G SOq.
Another reductive group is the special linear group SL(n) over a field k, the subgroup of matrices with determinant 1.
Roughly speaking, the Langlands reciprocity conjecture is the special case of the functoriality conjecture when one of the reductive groups is trivial.
Extending Chevalley's work, Michel Demazure andGrothendieck showed that split reductive group schemes over any nonempty scheme S are classified by root data.
Reductive groups over an arbitrary field are harder to classify, but for many fields such as the real numbers R or a number field, the classification is well understood.
In fact, this construction gives a one-to-one correspondence between compact connected Lie groups and complex reductive groups, up to isomorphism.
First, one can study the representations of a reductive group G over a field k as an algebraic group, which are actions of G on k-vector spaces.
A reductive group over a field k is called isotropic if it has k-rank greater than 0(that is, if it contains a nontrivial split torus), and otherwise anisotropic.
Every central simple algebra A over k determines a reductive group G SL(1,A), the kernel of the reduced norm on the group of units A* as an algebraic group over k.
A reductive group over a local field has a Tits system(B, N), where B is a parahoric group, and the Weyl group of the Tits system is an affine Coxeter group. .
For a compact Lie group K with complexification G, the inclusion from K into the complex reductive group G(C) is a homotopy equivalence, with respect to the classical topology on GC.
In seeking to classify reductive groups which need not be split, one step is the Tits index, which reduces the problem to the case of anisotropic groups. .
Over fields of characteristic greater than 3,all pseudo-reductive groups can be obtained from reductive groups by the"standard construction", a generalization of the construction above.
Reductive groups include some of the most important groups in mathematics, such as the general linear group GL(n) of invertible matrices, the special orthogonal group SO(n), and the symplectic group Sp2n.
On the other hand, the universal cover of SL(2,R)is not a real reductive group, even though its Lie algebra is reductive, that is, the product of a semisimple Lie algebra and an abelian Lie algebra.
A reductive group G over a field k is called split if it contains a split maximal torus T over k that is, a split torus in G whose base change to k¯{\displaystyle{\overline{k}}} is a maximal torus in G k¯{\displaystyle G_{\overline{k.
Generalizing these results,Tits showed that a reductive group over a field k is determined up to isomorphism by its Tits index together with its anisotropic kernel, an associated anisotropic semisimple k-group.
For a reductive group G over a field k that is complete with respect to a discrete valuation(such as the p-adic numbers Qp), the affine building X of G plays the role of the symmetric space.
Over perfect fields these are the same as(connected) reductive groups, but over non-perfect fields Jacques Tits found some examples of pseudo-reductive groups that are not reductive. .
Given two reductive groups and a(well behaved) morphism between their corresponding L-groups, this conjecture relates their automorphic representations in a way that is compatible with their L-functions.
These problems motivate the systematic study of G-torsors,especially for reductive groups G. When possible, one hopes to classify G-torsors using cohomological invariants, which are invariants taking values in Galois cohomology with abelian coefficient groups M, Hak, M.
For a reductive group G over a field of characteristic zero, all representations of G(as an algebraic group) are completely reducible, that is, they are direct sums of irreducible representations.
There are different types of objects for which the Langlands conjectures can be stated: Representations of reductive groups over local fields(with different subcases corresponding to archimedean local fields, p-adic local fields, and completions of function fields)Automorphic forms on reductive groups over global fields with subcases corresponding to number fields or function fields.
For any reductive group G with a Borel subgroup B, G/B is called the flag variety or flag manifold of G. Chevalley showed in 1958 that the reductive groups over any algebraically closed field are classified up to isomorphism by root data.