You will be given a definition of a task first, then some input of the task.
In this task, you will be presented with a context from an academic paper and you have to write an answerable question based on the context. Your questions can be extractive, abstractive, or yes-no questions.

The training objective is to minimize the negative likelihood of the aligned unanswerable question $ ilde{q}$ given the answerable question $q$ and its corresponding paragraph $p$ that contains the answer $a$ : L=-(q,q,p,a)DP(q|q,p,a;) where $\mathcal {D}$ is the training corpus and $ heta $ denotes all the parameters. Sequence-to-sequence and pair-to-sequence models are trained with the same objective.
Output:
What is the training objective of their pair-to-sequence model?