In the paper http://arxiv.org/pdf/hep-th/9301028.pdf pages 8-9 Pullin shows how to write the Einstein action in terms of tetrads [itex]e^a_I[/itex]. Part of the proof is: "...the last term yields [itex]e_M^{[a} e_N^{b]} \delta^M_{[I} \delta^K_{J]} C_{bK}^{\;\;\; N}[/itex]. It is easy to check that the prefactor in this expression is nondegenerate..."(adsbygoogle = window.adsbygoogle || []).push({});

Can somebody explain how you do this check?

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# Writing the Einstein action in terms of tetrads

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