According to the results from tables 1 and 2, regardless of the seed lexicon size, the bootstrapping approach does not suffer from semantic drift, i.e., if we seed the process with high-quality symmetric translation pairs, it is able to recover more pairs and add them as new dimensions of the bilingual vector space.
we also study the influence of applying different confidence estimation functions on top of the symmetry constraint (see sect 2.3), but we do not observe any improvement in the BLE results, regardless of the actual choice of a confidence estimation function.