Affine toric variety

Definition

An affine toric variety is a specific type of algebraic variety that can be constructed from a rational polytope and is associated with a torus acting on it. These varieties arise from the combinatorial data of fans and polytopes, where the points in the polytope correspond to monomials in a polynomial ring, giving a geometric interpretation to algebraic concepts. Affine toric varieties serve as a bridge between algebraic geometry and combinatorial geometry, allowing for the exploration of geometric properties through the lens of polytopes.

5 Must Know Facts For Your Next Test

1. Affine toric varieties can be realized as the spectrum of a polynomial ring modulo an ideal generated by monomials corresponding to the vertices of a polytope.
2. These varieties are particularly useful in algebraic geometry due to their combinatorial nature, making complex algebraic problems more tractable.
3. The dimension of an affine toric variety corresponds to the dimension of the polytope used in its construction.
4. Every affine toric variety has an associated dense open subset that corresponds to the regular semigroup associated with its fan.
5. Affine toric varieties can often be realized as quotients of affine spaces by the action of an algebraic group, providing a link to representation theory.

Review Questions

• How do affine toric varieties relate to polytopes and what role do they play in connecting algebra and geometry?
  • Affine toric varieties are directly linked to polytopes, as they are constructed using the vertices of these polytopes. Each vertex corresponds to a monomial, creating a geometric representation of algebraic structures. This connection allows us to apply combinatorial methods to solve problems in algebraic geometry, demonstrating how these two fields inform and enhance each other.
• What is the significance of fans in defining affine toric varieties, and how do they influence the properties of these varieties?
  • Fans provide the necessary combinatorial data that defines affine toric varieties. Each cone in the fan corresponds to a piece of the polytope, capturing essential information about how the torus acts on the variety. This structure influences various properties such as dimension, singularities, and how these varieties can be embedded in larger spaces.
• Evaluate the implications of affine toric varieties in broader mathematical contexts, particularly regarding their applications in other areas such as algebra or combinatorics.
  • Affine toric varieties have significant implications beyond their immediate definitions. They serve as tools for translating complex algebraic questions into combinatorial terms, making them more accessible for analysis. Their applications stretch into areas like mirror symmetry and tropical geometry, where insights from one domain can inform discoveries in another. Understanding these relationships enhances our grasp of both algebraic and geometric structures.

Related terms

Toric Variety: A toric variety is an algebraic variety that is constructed from combinatorial data associated with a fan or polytope, allowing for an action by a torus.

Fan: A fan is a collection of cones in a vector space that provide the combinatorial structure needed to define a toric variety.

Polytope: A polytope is a geometric object with flat sides, which can be used to describe the relationships between points, edges, and faces in the context of toric varieties.