Fixed something in the correlation calculation - first do the sum of squares and only do the square root in the reducer, otherwise using a combiner is not possible, it screws up the result; separated the calculation of similaroities from the prediction stage; tried to debug calculating the topk neighborhood in ReducerTopK but the TreeSet considers TopKRecords to be equal although they are not so it doesn't add new items; I changed the implementation of equals and compare to be the initial one Vaibhav did and I think it is correct,not sure what's going on