From the paper: "Our goal is to select a subset of the input sequence as a rationale. In order for the subset to qualify as a rationale it should satisfy two

From the paper: "Our goal is to select a subset of the input sequence as a rationale. In order for the subset to qualify as a rationale it should satisfy two criteria: 1) the selected words should be interpretable and 2) they ought to suffice to reach nearly the same prediction (target vector) as the original input. In other words, a rationale must be short and sufficient."