problem-set/geometry/tarski/t4.desc created : 07/16/86 revised : 08/17/89 Natural Language Description : Theorem 4: Every line segment has a midpoint. Versions : NOTE: all versions use a weighting scheme in which variables (and skolem functions) are weighted high and constants low. t4.ver1 : Original formulation of the axioms, from McCharen, Overbeek, & Wos [Aug. 1976]. created : 07/16/86. verified for ITP : Untested. translated for OTTER by : caw. verified for OTTER : no proof. t4.ver2 : Reformulation of the axioms, from Quaife [JAR 5 (1989)]. created : 07/25/89. verified for ITP : Untested. translated for OTTER by : caw. verified for OTTER : no proof. t4.ver3 : Reformulation of the axioms, from Quaife [JAR 5 (1989)]. created : 07/25/89. verified for ITP : Untested. translated for OTTER by : caw. verified for OTTER : no proof.