# Product of two Minkowksi metrics

1. Dec 2, 2013

### gentsagree

Can I say that $\eta^{ij}\eta_{km}=\delta^{i}_{k}\delta^{j}_{m}$?

Kind of in the same way that they yield one delta in the case where one of their indices is summed over?

Thanks

2. Dec 2, 2013

### tiny-tim

but $\eta^{ij}\eta_{km}$ is sometimes minus-one