For fixed z and a=19/4, b>=a
For fixed z and a=19/4, b=19/4
For fixed z and a=19/4, b=5
For fixed z and a=19/4, b=21/4
For fixed z and a=19/4, b=11/2
For fixed z and a=19/4, b=23/4
For fixed z and a=19/4, b=6