Does Anyone Know an Example of an Algebra Over GF(2) With Specific Properties?

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Discussion Overview

The discussion revolves around finding an example of an algebra over the field \(\mathbb{Z}_2\) that meets specific properties, including commutativity, associativity, the condition that \(x^3 = 0\) for all elements \(x\), and the existence of elements \(x\) and \(y\) such that \(x^2y \neq 0\.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests \(\mathbb{Z}_2[X]/(X^3)\) as a candidate, claiming it satisfies the first three properties and the last one with specific choices for \(x\) and \(y\).
  • Another participant counters that the third condition implies the algebra cannot have unity, thus disqualifying \(\mathbb{Z}_2[X]/(X^3)\) as a valid example.
  • There is a query about the validity of a direct approach to the problem, suggesting a method involving algebras rather than rings.
  • A participant proposes considering all polynomials over two variables \(x\) and \(y\) modulo the relations \(x^3 = y^3 = 0\), although this is later reiterated with a note on the implications of the conditions.
  • Another participant describes a specific algebra structure involving elements \{0, x, x^2, x^3, y, y^2, y^3\} and their combinations, but later retracts this due to the presence of elements that do not satisfy the cubic condition.
  • A later suggestion modifies the previous algebra by introducing a relation \((x)(y^2) = (x^2)(y)\), proposing it as a potential solution.

Areas of Agreement / Disagreement

Participants express differing views on the validity of proposed examples, with no consensus reached on a suitable algebra that meets all specified properties.

Contextual Notes

The discussion highlights the complexity of the conditions imposed on the algebra, particularly the implications of the cubic condition on the existence of unity and the structure of the algebra itself.

Lie
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Anyone know of an example of an algebra over the field \mathbb{Z}_2 with the following properties?
1. commutative;
2. associative;
3. x^3 = 0, for all x; and
4. Exists x and y such that x^2y \neq 0.

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What about \mathbb{Z}_2[X]/(X^3)? It satisfies your first three properties, and alse the last one with y=1 and x=X...
 
micromass,

Note that condition 3 implies that the algebra can not have unity. Therefore \mathbb{Z}_2[X]/(X^3) is not an example.
 
Oh sorry, I forgot to read "for all x" :frown: Well, I'll look for another example...
 
What goes wrong with the direct way to approach the problem? (e.g. like micromass's, except working with algebras rather than rings)
 
Ermm, can't you just take all polynomials over two variables x and y modulo the relation x^3=y^3=0 ?
 
Jamma said:
Ermm, can't you just take all polynomials over two variables x and y modulo the relation x^3=y^3=0 ?

Jamma, same remark:
Lie said:
micromass,

Note that condition 3 implies that the algebra can not have unity.[...]
 
Sorry, I didn't mean it like that, I should describe my algebra a bit better.

Take as our set of elements {0,x,x^2,x^3,y,y^2,y^3} and all multiples and linear combinations of them with the obvious rules of addition and multiplication subject to the condition that x^3=y^3=0.

There is no unity here.

[Edit:ignore me, this algebra has elements in it which don't cube to zero]
 
Last edited:
Ok, how about my algebra up there but with the relation (x)(y^2)=(x^2)(y).

It seems at a first glance that this works.
 

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