Task: Question Understanding
Input (English): According to the categories mentioned in BIBREF5 , irony can be classified into 3 classes: verbal irony by means of a polarity contrast, the sentences containing expression whose polarity is inverted between the intended and the literal evaluation; other types of verbal irony, the sentences that show no polarity contrast between the literal and intended meaning but are still ironic; and situational irony, the sentences that describe situations that fail to meet some expectations. As ironies in the latter two categories are obscure and hard to understand, we decide to only focus on ironies in the first category in this work.   Because of the lack of previous work and baselines on irony generation, we implement our model based on style transfer.  
 Question: What are the difficulties in modelling the ironic pattern?
Output (English): Extractive