About 2-dim non-abelian lie-algebra

Sarosh

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Joined
Jan 4, 2021
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I want to Calculate the Killing form for the two-dimensional non-abelian Lie algebra.

The killing form is defined as:
K: L × L —> F
K(x,y) = tr (ad_x • ad_y) for x , y in L (lie-algebra).

The two-dim non-abelian lie-algebra is
span {x, y} , [x,y] = y.

So, I would calculate the matrix of this lie-algebra.
Can I take the basis of it to be {x,y} ?
So the entries of the matrix are
K(x,x), K(x,y) = K(y,x), K(y,y) (it is a symmetrix matrix).

So, I need to compute the matrices: ad_x and ad_y.

Is
ad_x =
0 0
0 y

And

ad_y=
0 0
-y 0

?

It is just a liitle weird having this basis..
 
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