kockasinges

It seems, doesn't needs AI to solve this problem. I would like to get a bit more accurate answer.

So, please see this part of the exercise: moveX are the direction of the moving of tapes. (state, (sign1, sign2)) -> (state', (sign1', sign2'), (move1', move2', move3')) (START, (*,U,U)) -> (g1, (*,*,U), (1,1,0)) (g1, (U,U,U)) -> (g2, (*,*,U), (-2,0,0)) (g2, (U,U,U)) -> (STOP, (U,U,1), (0,0,0)) So, I have iterating through the tape and after that go back to the start of the tape, then STOP. But first of all, how to count characters on tape3?

How should I know, where is halfway in the word. These aren't fixed length.

I would like to construct a TM, that can accept words like these: tmtm or samesame. I plan to use up 3 tapes for this and copy all the symbols one by one from input to 2nd tape. Don't know, when and how should I examine back the copied characters. How should I know, where is half part?