Non-Commutative Hilbert Nullstellensatz?

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Discussion Overview

The discussion centers on the potential analog of Hilbert's Nullstellensatz in the context of non-commutative algebra and geometry. Participants explore the relationship between non-commutative algebras and geometric interpretations, questioning how concepts from commutative algebra might translate into non-commutative settings.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant expresses curiosity about whether there is a non-commutative version of Hilbert's Nullstellensatz, suggesting a correspondence between operator/matrix algebras and a "fuzzy" geometry.
  • Another participant questions the understanding of the Nullstellensatz, specifically whether it relates to functions defined on varieties or merely to the correspondence between commutative rings and algebraic varieties.
  • Concerns are raised about the existence of a direct analog of the vanishing set of polynomials in the non-commutative case.
  • A participant acknowledges a previous misunderstanding regarding the definition of non-commutative spaces, indicating that not all non-commutative geometries may have functions that form a non-commutative algebra.
  • Discussion includes the standard procedure of starting with non-commutative algebras, such as the Heisenberg algebra, and defining a "symbol map" to associate elements of this algebra with functions on commutative manifolds, though the uniqueness and well-defined nature of this map are questioned.
  • One participant expresses confusion about the necessity of knowing the "fuzzy geometry" beforehand to use the symbol map effectively.

Areas of Agreement / Disagreement

Participants express uncertainty and differing views regarding the relationship between non-commutative algebras and geometric interpretations, with no consensus reached on the existence or nature of a non-commutative Nullstellensatz.

Contextual Notes

Participants highlight limitations in their understanding of how non-commutative geometries relate to functions and algebras, as well as the challenges in defining mappings between non-commutative and commutative structures.

"pi"mp
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Hi,
In my very naive understanding of algebraic geometry, I get the impression that it's written in language of commutative algebra and the main theorem (at least at the basic level) is Hilbert's Nullstellensatz. I'm curious if there's an analog of the Nullstellensatz for non-commutative algebra/geometry?

What I'm envisioning would be a correspondence between some operator/matrix algebra and a "fuzzy" geometry.
Thanks!
 
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(nonsense removed)
 
Last edited:
Thanks! But I still have some confusions:

--I had never thought of the Nullstellensatz as having to do with functions defined on a variety. I had thought it was just a correspondence between commutative rings and algebraic varieties. Is there a direct analog of the vanishing set of polynomials in the non-commutative case?

--Also, you talk about defining a non-commutative space by starting with a non-commutative algebra as the functions on the space. But I vaguely remember reading somewhere that the problem with this is that not all non-commutative geometries will have functions defined on them that form a non-commutative algebra. Is this wrong?
 
I think.you are right, I took too much of a shortcut here. Interesting question, need to think about this.

Edit : actually, what I said is just wrong, sorry about that.
 
Last edited:
No worries, thank you. It seems like the standard procedure is to start with some non-commutative algebra, like the Heisenberg algebra or the angular momentum algebra, and define a "symbol map" that associates an element in this algebra to a function on the ordinary commutative manifold. Now, from what I read this certainly isn't a unique map, but I don't even understand how it can be well defined! It seems like you need to know before hand what the fuzzy geometry is going to be in order to use this. i.e. you need to know that the Heisenberg algebra will yield the non-commutative plane and that the angular momentum SU(2) algebra will yield the non-commutative sphere.

I'm not very clever with mathematical details, but I can usually appreciate the general program of some field. This I'm completely lost on!
 

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