let V be RealLinearSpace; :: thesis: for u, v, x, y being VECTOR of V holds u,v, Orte x,y,u, Orte x,y,v are_COrte_wrt x,y
let u, v, x, y be VECTOR of V; :: thesis: u,v, Orte x,y,u, Orte x,y,v are_COrte_wrt x,y
Orte x,y,u, Orte x,y,v // Orte x,y,u, Orte x,y,v by ANALOAF:17;
hence u,v, Orte x,y,u, Orte x,y,v are_COrte_wrt x,y by Def3; :: thesis: verum