Product of two Minkowksi metrics

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

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