Jacobi–Madden equation

28 year-old Painting Investments Worker Truman from Regina, usually spends time with pastimes for instance interior design, property developers in new launch ec Singapore and writing. Last month just traveled to City of the Renaissance.

In mathematics, the term affine Grassmannian has two distinct meanings; the concept treated in this article is the affine Grassmannian of an algebraic group G over a field k. It is an ind-scheme -- a limit of finite-dimensional schemes -- which can be thought of as a flag variety for the loop group G(k((t))) and which describes the representation theory of the Langlands dual group ^LG through what is known as the geometric Satake correspondence.

Definition of Gr via functor of points

Let k be a field, and denote by $k-\mathrm {Alg}$ and $\mathrm {Set}$ the category of commutative k-algebras and the category of sets respectively. Through the Yoneda lemma, a scheme X over a field k is determined by its functor of points, which is the functor $X:k-\mathrm {Alg} \to \mathrm {Set}$ which takes A to the set X(A) of A-points of X. We then say that this functor is representable by the scheme X. The affine Grassmannian is a functor from k-algebras to sets which is not itself representable, but which has a filtration by representable functors. As such, although it is not a scheme, it may be thought of as a union of schemes, and this is enough to profitably apply geometric methods to study it.

Let G be an algebraic group over k. The affine Grassmannian Gr_G is the functor that associates to a k-algebra A the set of isomorphism classes of pairs (E, φ), where E is a principal homogeneous space for G over Spec A[[t]] and φ is an isomorphism, defined over Spec A((t)), of E with the trivial G-bundle G × Spec A((t)). By the Beauville–Laszlo theorem, it is also possible to specify this data by fixing an algebraic curve X over k, a k-point x on X, and taking E to be a G-bundle on X_A and φ a trivialization on (X − x)_A. When G is a reductive group, Gr_G is in fact ind-projective, i.e., an inductive limit of projective schemes.

Definition as a coset space

Let us denote by ${\mathcal {K}}=k((t))$ the field of formal Laurent series over k, and by ${\mathcal {O}}=k[[t]]$ the ring of formal power series over k. By choosing a trivialization of E over all of Spec ${\mathcal {O}}$, the set of k-points of Gr_G is identified with the coset space $G({\mathcal {K}})/G({\mathcal {O}})$.

References

• 20 year-old Real Estate Agent Rusty from Saint-Paul, has hobbies and interests which includes monopoly, property developers in singapore and poker. Will soon undertake a contiki trip that may include going to the Lower Valley of the Omo.
  
  My blog: http://www.primaboinca.com/view_profile.php?userid=5889534