 The O -kernel of P{\rm  -}{\rm   is the subset of points which \mathcal{O}-see all the other points in P.
<meaning-changed>  The O -kernel of P{\rm  -}{\rm   is the subset of points which \mathcal{O}-see all the other points in P.
 The O -kernel of P{\rm -}{\rm Kernel is the subset of points which \mathcal{O}-see all the other points in P.