Hello I am having trouble with a slightly biological problem
I am given a regular expression $- [RK]-[LV]-[DE]-x(2)-Y$
this expression means that there is a string with the first position being an $R$ or a $K$, the second position an $L$ or a $V$, third a $D$ or an $E$, fifth and sixth can be anything, and the last position must hold a $Y$.
These characters represent amino acids with which there are twenty. (odds of first position being a match is $2/20 - 1/20+1/20$).
I am having trouble calculating the variance of the set assuming positional dependency.
thank you very much for your help and I will clarify anything if necessary.