SAND: Semantic Annotation of Numeric Data in Web Tables

A large portion of quantitative information about entities is expressed as Web tables, and these tables often lack proper schema and annotation, which introduces challenges for the purpose of querying and analysis. In this paper, we introduce SAND, a novel approach for annotating numeric columns of Web tables by linking them to properties in a knowledge graph. Our approach relies only on the semantic information readily available in knowledge graphs and not on contextual information that can be missing or labelled data which may be difficult to obtain. We show that our approach can reliably detect both semantic types (e.g., height) and unit labels (e.g., Centimeter) when the semantic type is present in the knowledge graph. Our evaluation on real-world web tables shows that our method outperforms by a large margin, in terms of accuracy, some of the state-of-the-art approaches on semantic labeling and unit detection.