Dieudonné determinant

In linear algebra, the Dieudonné determinant is a generalization of the determinant of a matrix to matrices over division rings and local rings. It was introduced by Dieudonné (1943).

If K is a division ring, then the Dieudonné determinant is a homomorphism of groups from the group GL_n(K) of invertible n by n matrices over K onto the abelianization K^×/[K^×, K^×] of the multiplicative group K^× of K.

For example, the Dieudonné determinant for a 2-by-2 matrix is

$\det \left({\begin{array}{*{20}c}a&b\\c&d\end{array}}\right)=\left\lbrace {\begin{array}{*{20}c}-cb&{\text{if }}a=0\\ad-aca^{-1}b&{\text{if }}a\neq 0\end{array}}\right..$

Properties

Let R be a local ring. There is a determinant map from the matrix ring GL(R) to the abelianised unit group R^×_ab with the following properties:

• The determinant is invariant under elementary row operations
• The determinant of the identity is 1
• If a row is left multiplied by a in R^× then the determinant is left multiplied by a
• The determinant is multiplicative: det(AB) = det(A)det(B)
• If two rows are exchanged, the determinant is multiplied by −1
• If R is commutative, then the determinant is invariant under transposition

Tannaka–Artin problem

Assume that K is finite over its centre F. The reduced norm gives a homomorphism N_n from GL_n(K) to F^×. We also have a homomorphism from GL_n(K) to F^× obtained by composing the Dieudonné determinant from GL_n(K) to K^×/[K^×, K^×] with the reduced norm N₁ from GL₁(K) = K^× to F^× via the abelianization.

The Tannaka–Artin problem is whether these two maps have the same kernel SL_n(K). This is true when F is locally compact but false in general.

See also

• Moore determinant over a division algebra

References

• Dieudonné, Jean (1943), "Les déterminants sur un corps non commutatif", Bulletin de la Société Mathématique de France, 71: 27–45, doi:10.24033/bsmf.1345, ISSN 0037-9484, MR 0012273, Zbl 0028.33904
• Rosenberg, Jonathan (1994), Algebraic K-theory and its applications, Graduate Texts in Mathematics, vol. 147, Berlin, New York: Springer-Verlag, ISBN 978-0-387-94248-3, MR 1282290, Zbl 0801.19001. Errata
• Serre, Jean-Pierre (2003), Trees, Springer, p. 74, ISBN 3-540-44237-5, Zbl 1013.20001
• Suprunenko, D.A. (2001) [1994], "Determinant", Encyclopedia of Mathematics, EMS Press