Determinant where the matrix entries may not be commutative

  • Context: Graduate 
  • Thread starter Thread starter leon1127
  • Start date Start date
  • Tags Tags
    Determinant Matrix
Click For Summary

Discussion Overview

The discussion centers on the definition of the determinant in the context of non-commutative matrices, specifically exploring applications to quaternions and Clifford algebras. Participants are examining whether traditional methods, such as minor expansion, are applicable in these non-commutative settings.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether the minor expansion of the determinant, which is typically defined over a field, still holds in non-commutative algebras.
  • Another participant suggests that the definition of the determinant may not assume commutativity, indicating that it could potentially work in non-commutative contexts, though they express uncertainty about this idea.
  • A third participant proposes that a useful definition of the determinant could be derived by representing a finite dimensional algebra over the reals as an algebra of real matrices, allowing for the computation of a real-valued determinant.
  • One participant notes that while the definition of determinant is straightforward for real or complex matrices, they are unsure if the Laplace expansion applies to quaternionic matrices, which could have implications for the norm function in Clifford algebras.
  • Another participant mentions finding various resources on "noncommutative determinant" that may provide useful definitions.

Areas of Agreement / Disagreement

Participants express uncertainty and differing viewpoints regarding the applicability of traditional determinant definitions in non-commutative settings. No consensus is reached on whether the minor expansion or Laplace expansion can be applied to quaternionic matrices.

Contextual Notes

The discussion highlights limitations related to the assumptions of commutativity in determinant definitions and the potential need for new definitions or approaches in the context of non-commutative algebras.

leon1127
Messages
484
Reaction score
0
I am trying to find definition of determinant where the matrix entries may not be commutative, for instance quaternions or Clifford algebras. Does the minor expansion of determinant over a field still work over a non-commutative algebra?
 
Physics news on Phys.org
leon1127 said:
I am trying to find definition of determinant where the matrix entries may not be commutative, for instance quaternions or Clifford algebras. Does the minor expansion of determinant over a field still work over a non-commutative algebra?

http://www.math.ucdavis.edu/~daddel...plications/Determinant/Determinant/node3.html

It doesn't seem like the definition assume commutativity. So, I guess it would work.

I'm totally not sure about this. I'm just throwing this thought in the air.
 
A google search on "noncommutative determinant" turns up several hits -- maybe one will have a useful definition?
 
My gut says that a useful definition of determinant could be defined as follows:

Your algebra A is a finite dimensional algebra over the reals -- I think that implies that it can be represented as an algebra of real matrices. So you can view your matrix over A as a matrix over R, and take the (real-valued!) determinant of that.
 
Hurkyl said:
My gut says that a useful definition of determinant could be defined as follows:

Your algebra A is a finite dimensional algebra over the reals -- I think that implies that it can be represented as an algebra of real matrices. So you can view your matrix over A as a matrix over R, and take the (real-valued!) determinant of that.

However, that is not that I am working with. I am playing with Clifford algebra and it is known that every element of Cl(p+1, q+1) can be represented by M(2, Cl(p,q)) and M(n, T) where T = R, C or H. Of course the definition of determinant is trivial when T = R or C, but I am not sure if the Laplace expansion still works on quaternionic matrices. If I can compute the determinant in that case, it will suggest the norm function for Cl(p+1, q+1).

Thank you for your suggestion by the way. I searched with the keyword pseudodeterminant while the suggested keyword 'noncommutative determinant' is more obvious. :cry:
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 14 ·
Replies
14
Views
5K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 8 ·
Replies
8
Views
2K