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This is a homework problem. Could anyone tell me the meaning of the symbols $i_{X},i_{Y}$ here? Thanks a lot.

Also, does $\Omega^{*}(M)$ here mean the exterior algebra bundle on the manifold $M$?

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The notation $i_X$ here is the interior product, which is just contraction with the first slot: for a $k$-form $\omega$, $i_X \omega$ is the $k-1$-form defined by $i_X \omega(Y_2,\ldots,Y_k) = \omega(X,Y_2,\ldots,Y_k).$

On the second point, you're basically right: $\Omega^*(M)$ usually refers to the space of sections of the exterior algebra of the cotangent bundle, i.e. $\Omega^*(M) = \Gamma(M, \Lambda T^*M)$ where $\Lambda T^*M = \oplus_{k=0}^m \Lambda^k (T^*M).$ That is, $\Omega^*(M)$ is just the space of all (smooth global) differential forms (possibly of mixed order) on $M$.

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  • $\begingroup$ So, $di_{X}$ and $i_{X}d$ mean $d\cdot i_{X}$ and $ i_{X} \cdot d$ where $d$ is the standard degree +1 antiderivation? $\endgroup$ – Aritro Pathak Oct 23 '17 at 3:10
  • $\begingroup$ @AritroPathak: they mean the compositions $d \circ i_X, i_X \circ d.$ $\endgroup$ – Anthony Carapetis Oct 23 '17 at 3:13
  • $\begingroup$ Yes sorry for the wrong tex command, I meant $\circ$ when I wrote $\cdot$. $\endgroup$ – Aritro Pathak Oct 23 '17 at 3:14

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