Abelian variety

Definition

An abelian variety is a complete algebraic variety that has a group structure, meaning it can be equipped with a law of addition that is compatible with its geometry. This concept extends the idea of elliptic curves to higher dimensions, allowing for the study of more complex algebraic structures while retaining many properties similar to those of elliptic curves, such as the existence of a canonical divisor and the ability to be defined over any field.

5 Must Know Facts For Your Next Test

1. Abelian varieties can be defined over any field, including finite fields and complex numbers, making them a central object of study in algebraic geometry.
2. An important property of abelian varieties is that they have a group structure, meaning you can add points on the variety using a well-defined operation.
3. They are complete algebraic varieties, meaning they contain all their limit points and thus have no 'holes' in their structure.
4. Abelian varieties generalize elliptic curves to higher dimensions, providing a framework for studying complex functions and arithmetic properties.
5. The study of abelian varieties is crucial in understanding the connection between geometry and number theory, particularly through concepts like the Mordell-Weil theorem which discusses rational points on these varieties.

Review Questions

• How do abelian varieties generalize elliptic curves and what implications does this have for their study in higher dimensions?
  • Abelian varieties generalize elliptic curves by extending the concept from one-dimensional to higher-dimensional spaces while maintaining similar group properties. This means that just like elliptic curves have a well-defined addition operation for points on the curve, abelian varieties allow for this operation in multiple dimensions. This generalization opens up new avenues for research in algebraic geometry, allowing mathematicians to investigate more complex structures and their relationships with number theory.
• Discuss the significance of the Jacobian in relation to abelian varieties and how it connects to algebraic curves.
  • The Jacobian is a critical construct associated with a smooth projective curve, serving as an example of an abelian variety. It encapsulates important information about line bundles on the curve and allows for the study of morphisms between curves. The connection highlighted by the Torelli Theorem asserts that knowing the Jacobian provides sufficient information to recover the original curve, illustrating how deeply intertwined the concepts of abelian varieties and algebraic curves are within algebraic geometry.
• Evaluate the impact of Weil conjectures on our understanding of abelian varieties and their properties in algebraic geometry.
  • The Weil conjectures significantly advanced our understanding of abelian varieties by linking their geometric properties with number-theoretic aspects through zeta functions. These conjectures propose deep relationships between topology and algebraic geometry, implying that studying abelian varieties can yield insights into rational points over finite fields. The resolution of these conjectures has opened pathways to modern techniques in arithmetic geometry, emphasizing how abelian varieties play a pivotal role in bridging different mathematical disciplines.

Related terms

Jacobian: The Jacobian of a smooth projective curve is an abelian variety that parametrizes line bundles on the curve and plays a key role in the study of algebraic geometry.

Torelli Theorem: The Torelli Theorem states that the abelian variety associated with a smooth projective curve can be reconstructed from its Jacobian, linking the geometry of the curve to its associated abelian variety.

Weil conjectures: A set of conjectures proposed by André Weil concerning the zeta function of algebraic varieties over finite fields, which connect topology, algebraic geometry, and number theory.