The APLHA_I CLI option accepts a float for what should (according to the paper) be a vector of floats (or more correctly a path to a SequenceFile containing word, alpha_i pairs for each word in the respective dictionary). The current MapReduce NB implementation treats APLHA_I as a constant float where it should be a vector (ALPHA) of floats (smoothing parameter per word).
However as (Rennie et al.) sec 2.2 uses a constant ALPHA_I = 1 and the NB implementation defaults to APLHA_I = 1 and is an implementation of Rennie, there is not really a problem.
To avoid confusion, I think its a good idea to remove the option to set ALPHA_I and to keep ALPHA_I a constant 1.0 in NB.