Made Easy Book

Question

• A.  114 

Comments

answer here given is wrong. how they are merging state 2 and 3?
the reg.exp of the language accepted by state 2 is a*b(ab)*, and by state 3 is a*b(ab)*a.

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Regex is correct for the final FA but the final FA is not equivalent to the FA in Question.
 

For more learning and visualizations you may use : 

1. Finite-State Machine Simulator: https://ivanzuzak.info/noam/webapps/fsm_simulator/
2. Regex Comparison (Although NP-Hard): https://bakkot.github.io/dfa-lib/regeq.html

Answer 1

first of all understand that for a single language we have many NFAs and DFAs so there is also many regular expressions are possible . so it is one of them . 

now to find Regular Expression from FInitte Automata we have different algorithms . 

there is also  method – STATE REMOVAL METHOD by this ive done this question .

here this is ...

Answer 2

Know that the regex is not unique for a given FA; 

With that said, the answer is wrong since we can have a counter-example - string ”bb“ shall be rejected by the FA but is produced by the regex.

You may find a correct answer and approach in the attached image :

 

 

 

 

 

 

 

 

 

More resources and explanation is mentioned by me in the comment: https://gateoverflow.in/409376/made-easy-book?show=409441#c409441