assume [A,B,C,O,L] : (point(A) & point(B) & point(C) & point(O) & line(L) & inc_po_l(A,L) & inc_po_l(B,L) & inc_po_l(C,L) & inc_po_l(O,L) & bet(A,O,B) & bet(A,O,C))

infer (col(B,C,O))
infer (bet(B,C,O) | bet(C,B,O))

  case (bet(B,C,O))
  infer (bet(O,C,B))
  infer (nbet(B,O,C))
  lookup (nbet(B,O,C))

  case (bet(C,B,O))
  infer (bet(O,B,C))
  infer (nbet(B,O,C))
  lookup (nbet(B,O,C))
