Aggregate bigram model and EM

If anyone is interested in playing with the aggregate bigram model, I've got an implementation that you can download and build (provided you have a c++ compiler). Here's the source code. If you want a sample corpus to train on, here's the Brown corpus, and here's some test data. This isn't written to be useful except as a way to play with ABMs, which have kind of strange behavior that might be worth exploring.

To get things running, after downloading, you might try the following on a Unixy terminal (like one of the Linux machines in the lab) or in a Mac OS X terminal:

g++ -O3 -o abm abm.cc
./abm brown.txt chomsky.txt

This will compile the ABM trainer, build a model using the Brown corpus, and then evaluate the model on the contents of chomsky.txt. If you want to change aspects of the model or training (the number of classes, the initialization strategy, the number of iterations), you'll need to edit abm.cc and make changes to the relevant variables and recompile.