This paper introduces a novel approach called title phrase generation (TPG) for unsupervised keyphrase generation (UKG), leveraging a pseudo label generated from a document title. Previous UKG method extracts all phrases from a corpus to build a phrase bank, then draws candidate absent keyphrases related to a document from the phrase bank to generate a pseudo label. However, we observed that when separating the document title from the document body, a significant number of phrases absent from the document body are included in the title. Based on this observation, we propose an effective method for generating pseudo labels using phrases mined from the document title. We initially train BART using these pseudo labels (TPG) and then perform supervised fine-tuning on a small amount of human-annotated data, which we term low-resource fine-tuning (LRFT). Experimental results on five benchmark datasets demonstrate that our method outperforms existing low-resource keyphrase generation approaches even with fewer labeled data, showing strength in generating absent keyphrases. Moreover, our model trained solely with TPG, without any labeled data, surpasses previous UKG method, highlighting the effectiveness of utilizing titles over a phrase bank. The code is available at https://github.com/kangnlp/low-resource-kpgen-through-TPG.

We propose a novel unsupervised keyphrase extraction approach, called SAMRank, which uses only a self-attention map in a pre-trained language model (PLM) to determine the importance of phrases. Most recent approaches for unsupervised keyphrase extraction mainly utilize contextualized embeddings to capture semantic relevance between words, sentences, and documents. However, due to the anisotropic nature of contextual embeddings, these approaches may not be optimal for semantic similarity measurements. SAMRank as proposed here computes the importance of phrases solely leveraging a self-attention map in a PLM, in this case BERT and GPT-2, eliminating the need to measure embedding similarities. To assess the level of importance, SAMRank combines both global and proportional attention scores through calculations using a self-attention map. We evaluate the SAMRank on three keyphrase extraction datasets: Inspec, SemEval2010, and SemEval2017. The experimental results show that SAMRank outperforms most embedding-based models on both long and short documents and demonstrating that it is possible to use only a self-attention map for keyphrase extraction without relying on embeddings. Source code is available at https://github.com/kangnlp/SAMRank.

Recently, there has been increased interest in utilizing characters or subwords for natural language processing (NLP) tasks. However, the effect of utilizing character, subword, and word-level information simultaneously has not been examined so far. In this paper, we propose a model to leverage various levels of input features to improve on the performance of an supersense tagging task. Detailed analysis of experimental results show that different levels of input representation offer distinct characteristics that explain performance discrepancy among different tasks.