# 'Symmetrisation Notation' - What is it?

1. Aug 1, 2012

### InsertName

I'm reading Hobson, Efstathiou and Lasenby, where on page 490, some notation is used that I am not familiar with.

In the rather long equation (17.62), some terms contain things like

$\partial_{(\mu} h^{\rho}_{\nu)}$.

The author(s) then says "where we have made use of the symmetrisation notation discussed in Chapter 4."

I've tried looking in Chapter 4 but it's not at all clear what is going on, so I came here :)

2. Aug 1, 2012

### Bill_K

The indices within the parentheses are understood to be totally symmetrized. So

hρν) = ½(∂μhρν + ∂νhρμ)

3. Aug 1, 2012

### InsertName

Thanks Bill_K!