First time here? Checkout the FAQ!
0 votes
Let A = {<M>|M is a TM and L(M) is regular}. Then A is _________

a) Decidable language and regular language

b) Undecidable but partially decidable

c) Totally not decidable

d) Decidable language but not regular language
asked in Theory of Computation by Veteran (51.7k points)   | 65 views
I think C, since we can take one Tyes = a and Tno = a^nb^n .Then Tyes subset of Tno.Hence not even R.E.

1 Answer

0 votes
Option B. According to Rice's theorem, anything non-trivial is undecidable. This is partially decidable, suppose the TM accepts a regular language, we can test this by passing all regular strings one after another, sooner or later the TM is going to stop by accepting it because it accepts reg language. This process can be fastened by using dovetailing technique i.e processing n strings parallely. But suppose the given TM doesn't accept regular language then the TM would be running forever checking every regular string. Thus it is partially decidable.
answered by Active (1.2k points)  

Related questions

+1 vote
1 answer
asked in Theory of Computation by monty Active (1.1k points)   | 151 views
Top Users Feb 2017
  1. Arjun

    5274 Points

  2. Bikram

    4230 Points

  3. Habibkhan

    3842 Points

  4. Aboveallplayer

    3086 Points

  5. Debashish Deka

    2378 Points

  6. sriv_shubham

    2308 Points

  7. Smriti012

    2236 Points

  8. Arnabi

    2008 Points

  9. sh!va

    1672 Points

  10. mcjoshi

    1640 Points

Monthly Topper: Rs. 500 gift card

20,846 questions
26,001 answers
22,098 users