Help me check the Jacobi identity regards the Lie bracket \sum_(cyclic) [X, [Y,Z]] = 0. This notation means that one permutes X,Y,Z cyclically and one takes the sum of the resulting terms. Written out, \sum_(cyclic) [X, [Y,Z]] = [X,[Y,Z]] + [Y,[Z,X]] + [Z,[X,Y]]. This is the exercise 14.11 from An Introduction to Manifolds by Tu.