A TM to accept EVEN-EVEN (a collection of all strings with an even number of a's and an even number of b's) can be based on the algorithm:Move up the string, changing as to AsMove down the string, changing bs to BsModified algorithm: To avoid the problem of crashing on the way down the $Tape$, change the letter in the first cell to an $X$ (if it's an $a$) and to a $Y$ (if it's a $b$). This way we can recognize the left end of the tape.So far I have this but am not sure how to implement the modified algorithm (note: the e's from start to halt mean empty):Any help is appreciated!
How to draw a Turing Machine for Even-Even
turing machines