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isProjective -- whether a variety is projective

Usage:

isProjective X
Inputs:
- X, a variety,
Outputs:
- a Boolean value,

Description

This method essentially returns whether $X$ was defined using Proj or Spec.

i1 : S = QQ[x,y,z]

o1 = S

o1 : PolynomialRing

i2 : isProjective Proj S

o2 = true

i3 : isProjective Spec S

o3 = false

Caveat

This method does absolutely no well-definedness checks and is very primitive. To check well-definedness use isWellDefined instead.

See also

isProjective(NormalToricVariety) -- whether a toric variety is projective

Ways to use isProjective:

isProjective(ProjectiveVariety)
isProjective(Variety)

For the programmer

The object isProjective is a method function.

The source of this document is in Varieties/doc-varieties.m2:334:0.