alright, i've been working on this assignment for awhile but these are the two i couldn't get...so if someone could point me in the right direction, it would be appreciated 1. L9 = {<M, w> | M is a TM, M on input w moves its head left at some point during its computation on w}. Show that L9 is decidable. 2. L10 = {<M, w> | M is a TM, at some point in its computation, M on input w moves its head left when the head is on the left-most tape cell}. Show that L10 is not decidable. thanks in advance

well, i have no fucking clue what these questions are about. however, i will take a shot in the dark. L9 is decidable, as in, you can tell if operation w occurred, because you are guaranteed that M moves its head to the left. so if M moves it's head to the left, w was input. L10 is not decidable because w could be input without you knowing (if the head is not on the left-most tape cell.) therefore you cannot know if w was input.