Unified Training for Cross-Lingual Abstractive Summarization by Aligning Parallel Machine Translation Pairs

Cross-lingual summarization (CLS) is essential for enhancing global communication by facilitating efficient information exchange across different languages. However, owing to the scarcity of CLS data, recent studies have employed multi-task frameworks to combine parallel monolingual summaries. These methods often use independent decoders or models with non-shared parameters because of the mismatch in output languages, which limits the transfer of knowledge between CLS and its parallel data. To address this issue, we propose a unified training method for CLS that combines parallel machine translation (MT) pairs with CLS pairs, jointly training them within a single model. This design ensures consistent input and output languages and promotes knowledge sharing between the two tasks. To further enhance the model's capability to focus on key information, we introduce two additional loss terms to align the hidden representations and probability distributions between the parallel MT and CLS pairs. Experimental results demonstrate that our method outperforms competitive methods in both full-dataset and low-resource scenarios on two benchmark datasets, Zh2EnSum and En2ZhSum.