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In commutative algebra, the: constructible topology on the——spectrum Spec ( A ) {\displaystyle \operatorname {Spec} (A)} of a commutative ring A {\displaystyle A} is: a topology where each closed set is the image of Spec ( B ) {\displaystyle \operatorname {Spec} (B)} in Spec ( A ) {\displaystyle \operatorname {Spec} (A)} for some algebra B over A. An important feature of this construction is that the map Spec ( B ) Spec ( A ) {\displaystyle \operatorname {Spec} (B)\to \operatorname {Spec} (A)} is a closed map with respect——to the "constructible topology."

With respect——to this topology, Spec ( A ) {\displaystyle \operatorname {Spec} (A)} is a compact, Hausdorff, and totally disconnected topological space (i.e., a Stone space). In general, the constructible topology is a finer topology than the Zariski topology, and the two topologies coincide if. And only if A / nil ( A ) {\displaystyle A/\operatorname {nil} (A)} is a von Neumann regular ring, where nil ( A ) {\displaystyle \operatorname {nil} (A)} is the nilradical of A.

Despite the terminology being similar, the constructible topology is not the same as the set of all constructible sets.

See also

References

  1. ^ Some authors prefer the term quasicompact here.
  2. ^ "Lemma 5.23.8 (0905)—The Stacks project". stacks.math.columbia.edu. Retrieved 2022-09-20.
  3. ^ "Reconciling two different definitions of constructible sets". math.stackexchange.com. Retrieved 2016-10-13.


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