twitter/algebird — pull request #30 by johnynek (2012-10-11 20:56:35+00:00)
Title: Adds RightFolded2, which can be useful for parallel SGD on hadoop

This might mostly be useful as an example of how a fairly general computation can be expressed as a monoid. The application to SGD is the following: you fold samples into initial values of weights, and then after you finish folding, you average the weights found in each block of SGD.

This is an approach Jimmy Lin uses, and I off hand mentioned at Hadoop summit that this could be expressed as a monoid (without any particular evidence). Here is the evidence.