TegFormer: Topic-to-Essay Generation with Good Topic Coverage and High Text Coherence

TL;DR

TegFormer is a novel Transformer-based model that improves topic coverage and text coherence in topic-to-essay generation by integrating domain-specific contexts and leveraging large-scale pre-trained language models.

Contribution

It introduces a Topic-Extension layer and an Embedding-Fusion module to enhance topic relevance and linguistic quality in generated essays.

Findings

Outperforms state-of-the-art methods in automatic evaluations

Achieves higher human-rated coherence and topic coverage

Both proposed modules significantly improve performance

Abstract

Creating an essay based on a few given topics is a challenging NLP task. Although several effective methods for this problem, topic-to-essay generation, have appeared recently, there is still much room for improvement, especially in terms of the coverage of the given topics and the coherence of the generated text. In this paper, we propose a novel approach called TegFormer which utilizes the Transformer architecture where the encoder is enriched with domain-specific contexts while the decoder is enhanced by a large-scale pre-trained language model. Specifically, a \emph{Topic-Extension} layer capturing the interaction between the given topics and their domain-specific contexts is plugged into the encoder. Since the given topics are usually concise and sparse, such an additional layer can bring more topic-related semantics in to facilitate the subsequent natural language generation. Moreover, an \emph{Embedding-Fusion} module that combines the domain-specific word embeddings learnt from the given corpus and the general-purpose word embeddings provided by a GPT-2 model pre-trained on massive text data is integrated into the decoder. Since GPT-2 is at a much larger scale, it contains a lot more implicit linguistic knowledge which would help the decoder to produce more grammatical and readable text. Extensive experiments have shown that the pieces of text generated by TegFormer have better topic coverage and higher text coherence than those from SOTA topic-to-essay techniques, according to automatic and human evaluations. As revealed by ablation studies, both the Topic-Extension layer and the Embedding-Fusion module contribute substantially to TegFormer's performance advantage.