The group GL2(F2) is non-abelian

The Mathematician — Mon, 05 Dec 2022 13:00:40 +0000

We will show that

GL_2(\mathbb{F}_2)

is non-abelian.

Proof. We have seen here that the elements of

GL_2(\mathbb{F}_2)

are as follows:

GL_2(\mathbb{F}_2) = \{ \begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix}, \begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix}, \begin{pmatrix} 1 & 1 \\ 1 & 0 \end{pmatrix}, \begin{pmatrix} 1 & 1 \\ 0 & 1 \end{pmatrix}, \begin{pmatrix} 0 & 1 \\ 1 & 1 \end{pmatrix}, \begin{pmatrix} 1 & 0 \\ 1 & 1 \end{pmatrix} \}.

We want to show that there exist two matrices

A,B \in GL_2(\mathbb{F}_2)

such that

AB \neq BA

. We will take:

A = \begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix} \quad \text{and} \quad B = \begin{pmatrix} 1 & 1 \\ 1 & 0 \end{pmatrix}.

Then we get:

AB = \begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix} \begin{pmatrix} 1 & 1 \\ 1 & 0 \end{pmatrix} = \begin{pmatrix} 1 & 0 \\ 1 & 1 \end{pmatrix},

and

BA = \begin{pmatrix} 1 & 1 \\ 1 & 0 \end{pmatrix} \begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix} = \begin{pmatrix} 1 & 1 \\ 0 & 1 \end{pmatrix},

Therefore, we see that

AB \neq BA

. So,

GL_2(\mathbb{F}_2)

is non-abelian.

GL2(F2) is non-abelian Archives - Epsilonify