Little Mouse (小老鼠)

1. The mouse in the original graph of the inequality fun(x,y) > 0 has no mouth.

2. Add a circle ( mouth(x,y) = 0 ) as the border line of the mouth.
    Graph fun(x,y) * mouth(x,y) > 0.

3. Add the boundary curves of the inequality regions which will be colored black or white.

4. The red and green meshed regions will be colored black and white, respectively.

5. Color the inequality regions black or white.

6. The finished result.

( Softwares used: gnuplot, Graph )