The alphabet $A=\{a,b\}$ will be used throughout this coursework. The languages are:

$L_1$ which has exactly one $b$ but any number of as$.$

$L_3$ which contains exactly two as or exactly two bs$,$ although not necessarily adjacent.

$L_4$ which has all the bs appearing before any of the as$,$ or all the as appearing before any of the bs$.$

$L_5$ where there can be any number of bs but the number of as must be even, although the as do

not have to be adjacent.

$L_2$ which has an odd number of bs and an even number of as$.$