Varieties: Definitions

Basics

  • For \(V\) a affine variety, what is \(k[V]\)? What is \(k(V)\)?
  • What is a Noetherian space?
  • What is \({\mathcal{O}}_X\)?
  • How is \({\mathcal{O}}_X\) defined for \(X \subseteq {\mathbb{A}}^n\)?
  • What are the Zariski closed subsets of \({\mathbb{A}}^n\)?
  • What are the maximal ideals of \({\mathcal{O}}_X(X)\)?
  • What is a distinguished open set?
  • Types of varieties:
    • What is an affine variety? A projective variety?
    • What is an irreducible subset of an affine variety?
    • What is a proper variety?
    • What is a complete variety?
    • What is a normal affine variety?
    • What is a Fano variety?
    • What is a Calabi-Yau variety?
    • What is a toric variety?
  • Properties of varieties
    • What is the dimension of an affine variety?
    • What is the degree of a variety?
    • What is a smooth point of a variety? A singular point?
    • What is a separated variety?
  • Constructions:
    • What is the Unsorted/normalization of an affine variety?
    • What is the projective closure of an affine variety
    • Given a projective variety \(X\), what is its affine cone?
    • What is the Hilbert function of a variety? The Hilbert polynomial?
  • What is the rational function field \(\kappa_X\) of an affine variety?
  • What does it mean for elements of \(\kappa_X\) to be algebraically independent?
  • What is a hyperplane section?
    • What is the hyperplane at \(\infty\) of \({\mathbb{P}}^n\) in coordinates?
  • What is the degree of a \(k{\hbox{-}}\)dimensional subvariety of \({\mathbb{P}}^n\)?
  • What is the Néron-Severi group?
  • Special bundles:
    • What is the canonical bundle? The anticanonical? Pluricanonical bundles?
    • What is the tautological bundle?
    • What is the Serre twisting line bundle?
    • What does it mean for a bundle to be positive?
  • What is the Segre embedding?
  • Singularities:
    • What is the Zariski tangent space?
    • What is a simple/smooth/regular/non-singular point of an affine variety?
    • What is a cuspidal singularity?
    • What is a nodal singularity?
    • What is a normal crossing singularity?
    • What is a local complete intersection?
  • What is an embedding of projective varieties?
  • What is the blowup of a point? The blowdown?
    • What is the proper transform? The strict transform?
    • What is the exceptional curve/divisor?
  • What is a Chow variety?
  • What is the Grassmannian?
  • What is a tangent cone?
  • What is a dual variety?
  • What is a hypersurface?
  • What is a very general hypersurface?
  • What does it mean to be unirational?
  • What does it mean to be ruled?
    • What does it mean to be uniruled?
  • What is a scroll?
  • What is the gonality of a curve?
  • What is a linear series?
  • What is specialization?

Morphisms

  • What is a regular function?
  • What is a Unsorted/birational?
  • What is a dominant morphism between varieties?
  • What is a birational morphism?
  • What is a rational function on a variety?
  • What is a finite morphism?
  • What is a quasi-finite morphism?
  • What is the degree of a morphism?
  • What is a closed morphism?
  • What is a rational map of affine varieties?
  • What is the indeterminacy set of a rational map?