Hi,

Have a few questions regarding usage of infinite loops:

1. For the language of <M,w> where M runs on an infinite number of cells while processing w, if I wanted to show this was in RE I could design a TM that would run M on w and check whether it read a blank cell + moved to the right for |Q|+1 steps, in which case it would accept, and otherwise reject?

2. Why couldn't we use this logic to show that the following is also in R (i.e. accept if M read 'blank' for |Q|+1 steps - it surely won't go left three times in a row and I can't think of any other 'infinite' situation in which it would): L = {<M> | in the computation of M(ε) the head never moves three times in a row left}

3. Also - two 'sure' infinite loops would be reading a blank for |Q|+1 steps and entering a repeating configuration (i.e. repeating some config. more than once)?

Thanks! :)