Tom Caylor wrote: > >Actually, in reviewing the definition of Turing machine (it's been over >2 decades since I studied it) I agree with you. The Turing machine >leaves behind a memory of its past through its "writes" to the tape. >Maybe I don't understand what Wei Dai was saying with his setting of >the head back to the start of the tape. In order to get back to the >exact beginning *state* the Turing Machine would have to be instructed >to do an inverse of all of the writes it has done and then go back to >the start of the tape.
But there is not always a unique inverse. There may be two distinct previous states A and B which would lead to the same state C on the next step--in this case the dynamics are not reversible. Jesse --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~----------~----~----~----~------~----~------~--~---
