Originally Posted by

**ilikedmath** Instructions: Show that there are essentially only 2 models for the following axiom system:

*Undefined terms*: point, adjacent to, and color.

AXIOMS:

1. There are exactly 5 points.

2. If point A is adjacent to point B, then point B is adjacent to point A.

3. If point A is not adjacent to point B, then there exists a point C to which A and B are mutually adjacent.

4. Each point is assigned a color, red or green.

5. Any two adjacent points are assigned to different colors.