# Differentisl geometry internal contraction

1. Feb 5, 2013

Hi
I am struggling to see how the relation:
$(df:U)(dh:V)-(dh:V)(df:V)$ (1)
can be rewritten as:
$U(fdh:v)-V(fdh:U)-fdh:[U,V]$ (2)

I have tried expanding (1) out by making a scalar vector product of Udh:V but i don't think that is right and i am just not sure how best to proceed. It was annoyingly skipped over in class today, any help or suggestions would be appreciated.

2. Feb 12, 2013

### Kreizhn

I am very unclear as to what you are asking. Perhaps you could clarify? What is f,h,U,V? What does your : mean? Typically, I have seen contraction denoted by $\iota$ or $\lrcorner$, so I do not know how to read this.