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Projective Variety


A projective variety over a field k is an algebraic variety that admits a closed embedding into a projective space P_k^n. Its homogeneous defining equations describe a closed algebraic set in that space, with its induced scheme structure. Unlike a quasiprojective variety, it has no deleted boundary in the chosen projective embedding. For example, projective space and smooth plane curves are projective varieties.

Projectivity implies properness over k. On a projective variety, sections of powers of a line bundle define rational maps whose image dimensions measure its Iitaka dimension. A projective variety over C is compact in its analytic topology.


See also

Algebraic Variety, Iitaka Dimension, Kollar-Pardon Conjecture, Projective Space, Proper Morphism, Quasiprojective Variety

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References

Hartshorne, R. Algebraic Geometry. New York: Springer-Verlag, 1977.

Cite this as:

Weisstein, Eric W. "Projective Variety." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/ProjectiveVariety.html

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