13. An apparatus comprising: a storage that stores at least labeled training data that is composed in a source language; a storage that stores at least a particular document that is composed in a target language that differs from the source language; one or more processors that: (a) train a source language text classifier based on the labeled training data, thereby producing a source language model; (b) translate source language features from the source language model into a target language at least in part by selecting, for at least a particular source language feature of the source language features, and based at least in part on an expectation maximum, a particular target language translation of a plurality of possible target language translations of the particular source language feature; and (c) apply a target language classifier, which uses a target language model produced based at least in part on the selecting, to the particular document, thereby determining whether the particular document belongs to a particular class; wherein the one or more processors select the particular target language translation at least in part by: determining a first probability based at least in part on the particular target language translation during a first iteration; determining a second probability based at least in part on the particular target language translation during a second iteration; determining whether a difference between the first probability and the second probability is less than a specified threshold; in response to determining that the difference between the first probability and the second probability is less than the specified threshold, setting a final translation probability for the particular target language translation equal to the second probability; and selecting the particular target language translation based at least in part on the final translation probability.
13. An apparatus comprising: a storage that stores at least labeled training data that is composed in a source language; a storage that stores at least a particular document that is composed in a target language that differs from the source language; one or more processors that: (a) train a source language text classifier based on the labeled training data, thereby producing a source language model; (b) translate source language features from the source language model into a target language at least in part by selecting, for at least a particular source language feature of the source language features, and based at least in part on an expectation maximum, a particular target language translation of a plurality of possible target language translations of the particular source language feature; and (c) apply a target language classifier, which uses a target language model produced based at least in part on the selecting, to the particular document, thereby determining whether the particular document belongs to a particular class; wherein the one or more processors select the particular target language translation at least in part by: determining a first probability based at least in part on the particular target language translation during a first iteration; determining a second probability based at least in part on the particular target language translation during a second iteration; determining whether a difference between the first probability and the second probability is less than a specified threshold; in response to determining that the difference between the first probability and the second probability is less than the specified threshold, setting a final translation probability for the particular target language translation equal to the second probability; and selecting the particular target language translation based at least in part on the final translation probability. 17. The apparatus of claim 13 , wherein the one or more processors select the particular target language translation at least in part by determining a set of parameters that maximize a log likelihood of observations.