:: deftheorem Def3 defines DirPar ANALOAF:def 3 :
for V being RealLinearSpace
for b₂ being Relation of [: the carrier of V, the carrier of V:] holds
( b₂ = DirPar V iff for x, z being object holds
( [x,z] in b₂ iff ex u, v, w, y being VECTOR of V st
( x = [u,v] & z = [w,y] & u,v // w,y ) ) );