- < or > = open circle
- ≤ or ≥ = closed circle
⇒ open circle at (-2, 5) with a line to the left
⇒ closed circle at (-2, 3) with a line segment to an open circle at (0, 3)
⇒ closed circle at (0, 0) with a line segment to an open circle at (2, 0)
⇒ closed circle at (2, -3) with a line to the right
