Affine varieties, ideals and coordinate rings
Research context
postgraduate concept · established · As of 2026-10-10
Over an algebraically closed field k, polynomial zero sets V(I) have coordinate ring k[x1,...,xn]/I(V(I)).
Key knowledge
Over an algebraically closed field k, polynomial zero sets V(I) have coordinate ring k[x1,...,xn]/I(V(I)). The strong Nullstellensatz gives I(V(I))=radical(I), so geometric zero sets forget nilpotent thickening. The ideal (x²) and (x) define the same points in affine one-space but different quotient rings. An irreducible reduced affine variety has an integral-domain coordinate ring.
Values and equations
I(V(I))=sqrt(I); k[V]=k[x1,...,xn]/I(V)
- k
- Algebraically closed field
- I
- Polynomial ideal
- sqrt(I)
- Radical ideal
Conditions and scope
- The strong point/ideal correspondence uses an algebraically closed base field.
- The convention here reserves variety for reduced irreducible objects; some authors permit reducible varieties.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Author checked this English statement, displayed equation where present and stated hypotheses against these source locations: Chapters 2 and 4: Zariski topology, strong Nullstellensatz Theorem 2.16, coordinate rings and nonsingular points; Section 10.34: finite-type fields and radical ideals. The check is bounded to the recorded claims; no complete proof reconstruction, software proof replay or universal literature completeness is claimed.
2026-10-10 · Author source-body/statement/equation/domain check, with graph associations scoped individually. Separate independent content/source/inventory review is required before branch closure.
Entry details
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