OpenMath is the name of a markup language for specifying the meaning of mathematical formulae. Among other things, it can be used to complement MathML, a standard which mainly focuses on the presentation of formulae, with information about their semantic meaning. OpenMath can be encoded in XML or in a binary format. Coverage OpenMath consists of the definition of "OpenMath Objects", which is an abstract datatype for describing the logical structure of a mathematical formula and the definition of "OpenMath Content Dictionaries", or collections of names for mathematical concepts. The names available from the latter type of collections are specifically intended for use in extending MathML, and conversely, a basic set of such "Content Dictionaries" has been designed to be compatible with the small set of mathematical concepts defined in Content MathML, the non-presentational subset of MathML. History OpenMath has been developed in a long series of workshops and (mostly European) research projects that began in 1993 and continues through today. The OpenMath 1.0 Standard was released in February 2000, and revised as OpenMath 1.1 in October 2002. Two years later, the OpenMath 2.0 Standard was released in June 2004. OpenMath 1 fixed the basic language architecture, while OpenMath2 brought better XML integration, structure sharing and liberalized the notion of OpenMath Content dictionaries. OpenMath Society The OpenMath Effort is governed by the OpenMath Society, based in Helsinki, Finland. The Society brings together tool builders, software suppliers, publishers and authors. Membership is by invitation of the Societies Executive Committee, which welcomes self-nominations of individuals who have worked on OpenMath-related issues in research or application. As of 2007, Michael Kohlhase is president of the OpenMath society. He succeeded Arjeh M. Cohen, who was the first president. Example The well-known quadratic formula: would be marked up like this in OpenMath (the representation is an expression tree made up from functional elements like for function application or for variables): <OMOBJ xmlns="http://www.openmath.org/OpenMath"> <OMA cdbase="http://www.openmath.org/cd"> <OMS cd="relation1" name="eq"/> <OMV name="x"/> <OMA> <OMS cd="arith1" name="divide"/> <OMA> <OMS cdbase="http://www.example.com/mathops" cd="multiops" name="plusminus"/> <OMA> <OMS cd="arith1" name="unary_minus"/> <OMV name="b"/> </OMA> <OMA> <OMS cd="arith1" name="root"/> <OMA> <OMS cd="arith1" name="minus"/> <OMA> <OMS cd="arith1" name="power"/> <OMV name="b"/> <OMI>2</OMI> </OMA> <OMA> <OMS cd="arith1" name="times"/> <OMI>4</OMI> <OMV name="a"/> <OMV name="c"/> </OMA> </OMA> </OMA> </OMA> <OMA> <OMS cd="arith1" name="times"/> <OMI>2</OMI> <OMV name="a"/> </OMA> </OMA> </OMA> </OMOBJ> In the expression tree above symbols—i.e. elements like —stand for mathematical functions that are applied to sibling expressions in an