# Is every 3-Sasakian a Sasakian-Einstein manifold?

a short question: Is every 3-Sasakian manifold a Sasaki-Einstein manifold? If not, do you have an example? If yes, how can I prove this?

Thanks and best regards

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A hyperkähler manifold is Ricci-flat Kähler in a variety of ways -- that variety being $\mathbb{CP}^1$. – José Figueroa-O'Farrill Nov 22 '10 at 21:41