Symbolic math, especially tensor analysis and General Relativity. Inge Frick, Stockholm, late 70's to early 80's. Implemented in DEC-10 assembly language, then in several LISPs. Current version for Sun-3, based on Portable Standard LISP. "Sheep, a Computer Algebra System for General Relativity", J.E.F. Skea et al in Proc First Brazilian School on Comp Alg, W. Roque et al eds, Oxford U Press 1993, v2.