Rethinking the Value of Gazetteer in Chinese Named Entity Recognition

Gazetteer is widely used in Chinese named entity recognition (NER) to enhance span boundary detection and type classification. However, to further understand the generalizability and effectiveness of gazetteers, the NLP community still lacks a systematic analysis of the gazetteer-enhanced NER model. In this paper, we first re-examine the effectiveness several common practices of the gazetteer-enhanced NER models and carry out a series of detailed analysis to evaluate the relationship between the model performance and the gazetteer characteristics, which can guide us to build a more suitable gazetteer. The findings of this paper are as follows: (1) the gazetteer improves most of the situations that the traditional NER model datasets are difficult to learn. (2) the performance of model greatly benefits from the high-quality pre-trained lexeme embeddings. (3) a good gazetteer should cover more entities that can be matched in both the training set and testing set.Comment: Accepted by NLPCC 202

Knowledge Retrieval (KR)

Where is the Life we have lost in living? Where is the wisdom we have lost in knowledge? Where is the knowledge we have lost in information? — T.S. Eliot, The Rock, 1934. With the ever-increasing growth of data and information, finding the right knowledge becomes a real challenge and an urgent task. Traditional data and information retrieval systems that support the current web are no longer adequate for knowledge seeking tasks. Knowledge retrieval systems will be the next generation of retrieval system serving those purposes. Basic issues of knowledge retrieval systems are examined and a conceptual framework of such systems is proposed. Theories and Technologies such as theory of knowledge, machine learning and knowledge discovery, psychology, logic and inference, linguistics, etc. are briefly mentioned for the implementation of knowledge retrieval systems. Two applications of knowledge retrieval in rough sets and biomedical domains are presented. 1

Systematic review and meta-analysis of outcomes after liver resection in patients with hepatocellular carcinoma (HCC) with and without bile duct thrombus

INTRODUCTION: This meta-analysis aimed to compare perioperative and survival outcomes in patients who underwent hepatectomy with and without Bile Duct Tumour Thrombus (BDTT). METHODS: A comprehensive search of Cochrane Library, PubMed, MEDLINE and EMBASE was performed to identify relevant articles. The perioperative, postoperative and long term outcomes were compared. RESULTS: Eleven studies including 6051 patients met the inclusion criteria. The perioperative outcomes were comparable between the 2 groups. The BDTT group had higher proportion poorly differentiated tumours (OR = 1.87, X(2) = 10.00, df = 6, p = 0.002, I(2) = 40%), Lymphovascular invasion (LVI) (OR = 4.85, X(2) = 28.21, df = 9, p = <0.001, I(2) = 68%) and Macrovascular invasion (MVI) (OR = 5.41, X(2) = 8.73, df = 9, p = <0.001, I(2) = 0%). There was no difference in 1 and 3 year survival, however 5-yr survival was poorer in the BDTT group (OR = 0.37, X(2) = 37.04, df = 7, p = <0.001, I(2) = 81%). The mean difference (MD) in overall survival in the BDTT group was −20 months [−32.31, −7.06], p = 0.002, I(2) = 95%. CONCLUSION: Patients with HCC with BDTT had more advanced stage HCC with adverse histological features including higher rates of MVI, LVI and poor differentiation. Hepatectomy in this group of patients offers similar survival at 3 years but inferior long-term survival and should be considered when feasible