The OWL API is a Java API and reference implmentation for creating, manipulating and serialising OWL Ontologies. The latest version of the API is focused towards OWL 2
Welcome to the OpenMath website. OpenMath is an extensible standard for representing the semantics of mathematical objects. If you haven't heard about it before you might want to consult the overview.
T. Gruber, and G. Olsen. Principles of Knowledge Representation and Reasoning: Proceedings of the 4th International Conference (KR '94): Bonn, Germany: 1994, May, 24 - 27, page 258-269. Morgan Kaufmann Publishers, (1994)
V. Uren, E. Motta, M. Dzbor, and P. Cimiano. K-CAP '05: Proceedings of the 3rd international conference on Knowledge capture, page 75--82. New York, NY, USA, ACM, (2005)