1 votes 1 votes I have read that T.M does not accept ε , but then in questions I have read T.M taking input ε ? Well, if T.M can't accept ε then why we are giving T.M the input ε ? Thank you! Theory of Computation theory-of-computation turing-machine self-doubt decidability + – iarnav asked Oct 17, 2017 iarnav 680 views answer comment Share Follow See all 9 Comments See all 9 9 Comments reply Angkit commented Oct 17, 2017 reply Follow Share ϵ is the empty string. A Turing machine accepts ϵ if the start state of its finite control is an accepting state. 1 votes 1 votes iarnav commented Oct 17, 2017 reply Follow Share @Angkit Please see this - https://gateoverflow.in/153361/turing-machine-epsilon @srestha Please help! 0 votes 0 votes Angkit commented Oct 17, 2017 reply Follow Share https://gateoverflow.in/83694/turing-machine see it.. iarnav 1 votes 1 votes srestha commented Oct 17, 2017 reply Follow Share What does this mean "that TM not accepts epsilon"? That means TM has no input now. Simply u can think like this. TM only accept some strings(that means when there are some input) But, here TM has no input So, it cannot accept that clear? 0 votes 0 votes Shubhanshu commented Oct 17, 2017 reply Follow Share I have read that T.M does not accept ε I think you should write IT is undecidable that TM accepts ε. 2 votes 2 votes Arjun commented Oct 17, 2017 reply Follow Share @Shubhansu Exactly, otherwise that statement is giving the naswer "No" to the decidability question and hence making the undecidable problem decidable. 0 votes 0 votes iarnav commented Oct 19, 2017 reply Follow Share Thank you all, it makes sense now. Thanks. 0 votes 0 votes Shubhanshu commented Oct 19, 2017 reply Follow Share @Angkit ϵ is the empty string. A Turing machine accepts ϵ if the start state of its finite control is an accepting state. Is there any other way you know?? 0 votes 0 votes Arjun commented Oct 19, 2017 reply Follow Share He used "if" and not "iff" or else the problem would have become decidable :) 0 votes 0 votes Please log in or register to add a comment.