2 | 4. u1: Formula 5. v1: Formula List 6. ( f v.( (f) > 0)   f v1.( (f) > 0)  ( < v,v1 > ) = 0) 
 f (u.v).( (f) > 0)   f v1.( (f) > 0)  ( < u.v,v1 > ) = 0 ( f v.( (f) > 0)   f (u1.v1).( (f) > 0)  ( < v,u1.v1 > ) = 0) 
 f (u.v).( (f) > 0)   f (u1.v1).( (f) > 0)  ( < u.v,u1.v1 > ) = 0 |