Is an HMoE better than a flat MoE?
	• If we use the simple gating networks that can be fitted rapidly by IRLS, is an HMoE really more powerful than a flat MoE? – The textbook says it is but doesn’t say why. – An HMoE that uses a binary tree has the same number of degrees of freedom in the path probabilities as a single flat softmax over all experts. – But does the dependence on the input vector make the two ways of doing the gating different?