SUMEX: A hybrid framework for Semantic textUal siMilarity and EXplanation generation

Measuring semantic similarity between two pieces of text is a widely known problem in Natural language processing(NLP). It has many applications, such as finding similar medical notes of patients to accelerate the diagnosis process, plagiarism detection, and document clustering. Most state-of-the-art models are based on machine/deep learning and lack sufficient explanations for their results, limiting their adoption in critical domains like healthcare. This paper presents a hybrid framework SUMEX (Semantic textUal siMilarity and EXplanation generation) that uniquely combines ontology with a state-of-the-art embedding-based model for semantic textual similarity. The primary strength of the framework is that it explains its results in humanunderstandable natural language, which is vital in critical domains such as healthcare. Experiments have been conducted on two datasets of clinical notes using four embeddings: ScispaCy, BioWord2Vec, ClinicalBERT, and a customized Word2Vec trained on clinical notes. The SUMEX framework outperforms the embedding-based model on the benchmark datasets of ClinicalSTS by improving average precision scores by 7 % and reducing the false-positives-rate by 23 %. On the Patients Similarity Dataset, the average top-five and top-three precision scores were improved by 14% and 10%, respectively, using SUMEX. The SUMEX also generates explanations for its results in natural language. The domain experts evaluated the quality of the explanations. The results show that the generated explanations are of significantly good quality, with a score of 90 % and 93 % for measures of Completeness and Correctness, respectively. In addition, ChatGPT was also used for similarity score and generating explanations. The experiments show that the SUMEX framework performed better than the ChatGPT.