Knowledge engineering for large ontologies with sigma KEE 3.0. The suggested upper merged ontology (SUMO) is a large, comprehensive ontology stated in higher-order logic. It has co-evolved with a development environment called the Sigma knowledge engineering environment (SigmaKEE). A large and important subset of SUMO can be expressed in first-order logic with equality. SigmaKEE has integrated different reasoning systems in the past, but they either had to be significantly modified, or integrated in a way that multiple queries to the same theory required expensive full re-processing of the full knowledge base.par To overcome this problem, to create a simpler system configuration that is easier for users to install and manage, and to integrate a state-of-the-art theorem prover we have now integrated Sigma with the E theorem prover. The E distribution includes a simple server version that loads and indexes the full knowledge base, and supports interactive queries via a simple interface based on text streams. No special modifications to E were necessary for the integration, so SigmaKEE can be easily upgraded to future versions.