The postcritical set has 3 points if b = 0.
The postcritical set has 3 points if b = lambda1.
The postcritical set has 3 points if b = lambda2.
The postcritical set has 3 points if b = lambda1+lambda2.
Every Thurston map in this modular group Hurwitz class
has degree 2 and fewer than four postcritical points.
No Thurston map in this modular group Hurwitz class is a NET map.
These Thurston maps are rational.