To create a negative example from τ ∈ S, we randomly swapped one of the components of τ with another tuple τ ∈ S. One third of the time we swapped t 1 in τ for t 1 in τ , one third of the time we swapped their R's, and the remaining third of the time we swapped their t 2 's.
distinguishing positive and negative examples in this task is similar to the objectives optimized during training.