:: deftheorem defines out2 GTARSKI5:def 17 :
for S being non empty satisfying_Tarski-model satisfying_Lower_Dimension_Axiom TarskiGeometryStruct
for a, b being POINT of S
for A being Subset of S holds
( A out2 a,b iff ex c being POINT of S st
( between2 a,A,c & between2 b,A,c ) );