Even though we use a "local versus topical" feature split, which divides the features into two separate views on sense classification, there might be some natural dependencies between the features, since they are extracted from the same context, which may weaken the independence condition, and may sometime make the behavior of co-training similar to a self-training process.
as theoretically shown in (Abney, 2002), and then empirically in (Clark et al., 2003), co-training still works under a weaker independence assumption, and the results we obtain concur with these previous observations.