title: What is the output of XGboost using 'rank:pairwise'?
body: <p>I use the python implementation of XGBoost. One of the objectives is <code>rank:pairwise</code> and it minimizes the pairwise loss (<a href="https://github.com/dmlc/xgboost/blob/master/doc/parameter.md" rel="noreferrer">Documentation</a>). However, it does not say anything about the scope of the output. I see numbers between -10 and 10, but can it be in principle -inf to inf? </p>