:: deftheorem defines BK-model-Betweenness BKMODEL3:def 7 :
for b₁ being Relation of [:BK_model,BK_model:],BK_model holds
( b₁ = BK-model-Betweenness iff for a, b, c being Element of BK_model holds
( [[a,b],c] in b₁ iff BK_to_REAL2 b in LSeg ((BK_to_REAL2 a),(BK_to_REAL2 c)) ) );