Web-based Interactive Visualization of Non-Lattice Subgraphs (WINS) in SNOMED CT.

Non-lattice subgraphs are often indicative of structural anomalies in ontological systems. Visualization of SNOMED CT's non-lattice subgraphs can help make sense of what has been asserted in the hierarchical ("is-a") relation. More importantly, it can demonstrate what has not been asserted, or "is-not-a," using Closed-World Assumption for such subgraphs. A feature-rich web-based interactive graph-visualization engine called WINS is introduced, for supporting non-lattice based analysis of ontological systems such as SNOMED CT. A faceted search interface is designed for querying conjunctively specified non-lattice subgraphs. To manage the large number of possible nonlattice subgraphs, MongoDB is used for storing and processing sets of concepts, relationships, and subgraphs, as well as for query optimization. WINS' interactive visualization interface is implemented in the open source package D3.js. 14 versions of SNOMED CT (US editions from March 2012 to September 2018), with about 170,000 subgraphs in each version, were extracted and imported into WINS. Two types of non-lattice based ontology quality assurance (OQA) tasks were highlighted to demonstrate use cases of WINS in sense-making of such non-lattice subgraphs.