22 Jan
2009
22 Jan
'09
9:53 a.m.
On Wed, Jan 21, 2009 at 11:12 PM, Eugene Kirpichov
To my mind, in the map-reduce case you generally need a commutative monoid. Or, you need an extra infrastructure that mappend's only results from adjacent machines, or something like that.
This is a good paper on the stuff I'm talking about: http://citeseer.ist.psu.edu/blelloch90prefix.html It doesn't explicitly mention monoids but it's all about associative operations with identity. -- Dan