# Levi-Civita Symbol and indefinite metrics

1. Mar 25, 2015

### Geometry_dude

Let $(M,g)$ be an $n$-dimensional pseudo-Riemannian manifold of signature $(n_+, n_-)$ and define the Levi-Civita symbol via
$$\varepsilon_{i_1 \dots i_n} \, \theta^{i_1 \dots i_n} = n! \, \theta^{[1 \dots n]} = \theta^1 \wedge \dots \wedge \theta^n$$
where $\theta^1, \dots, \theta^n$ is a basis of covectors and the brackets denote the antisymmetrization operation.
With this definition I was able to prove the following formula for the determinant of a tangent space endomorphism (i.e. a "matrix") $A$
$$\det A = n! \, A^{1}{}_{[1} \cdots A^{n}{}_{n]}.$$
My first question is: How do I compute
$$\varepsilon_{i_1 \dots i_n} \varepsilon^{i_1 \dots i_n} \equiv \varepsilon_{i_1 \dots i_n} \, g^{i_1j_1} \cdots g^{i_n j_n}\, \varepsilon_{j_1 \dots j_n}$$
in a formal manner?
How do I compute the other common identities for the Levi-Civita Symbol like
$$\varepsilon_{i_1 \dots i_k j_{1} \dots j_{n-k}} \varepsilon^{j_{1} \dots j_{n-k} l_1 \dots l_k} = \, ?$$

I have browsed loads of differential geometry books, but none do this seemingly basic thing explicitly.

2. Mar 29, 2015

### Geometry_dude

Noone has any idea? Actually, I was trying to prove this to understand the Hodge operator.

Does anyone have a good reference?

The Levi-Civita symbol as defined here is just the standard one:

$$\varepsilon_{i_1 \dots i_n} = n! \, \delta^{[1}_{i_1} \cdots \delta^{n]}_{i_n}$$

3. Mar 29, 2015

### robphy

Have you seen the determinant expressions in http://en.wikipedia.org/wiki/Levi-Civita_symbol ?
Are you specifically looking for something that uses metrics with general signatures (so there may be factors of (-1) for each timelike direction)?

Look at the google book page from this google search: de felice alternating tensors

Last edited: Mar 29, 2015