sigma http://www.openmath.org/cd/sigma.ocd 2003-04-01 private Sigma Types for OM Declaration of symbols for types and objects An OpenMath object which uses any of the symbols here defined, has to use them in accordance with the definitions in ESPRIT deliverable 1.3.2b . Initial version: O. Caprotti and H. Elbers (July 2, 1998) Updated: O. Caprotti (March 5, 1999) Updated: O. Caprotti (May 20, 1999) added "mapsto", made a CDGroup SigmaType The type constructor of cartesian products. It takes a list of type-attributed variables and an OpenMath object. Pair The pairing constructor. It takes two OpenMath objects as first element and second element of the pair, and a third optional OpenMath object that represents the type of this pair. PairProj1 The first projection function. It satisfies sigma-reduction. PairProj2 The second projection function. It satisfies sigma-reduction.