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Decidable Problems of Regular Languages

Decidable Problems of Regular Languages. Answer:. Take the DFA that accepts and check if is accepted . Membership Question. Question:. Given regular language and string how can we check if ? . DFA. DFA. Question:. Given regular language how can we check

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Decidable Problems of Regular Languages

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  1. Decidable ProblemsofRegular Languages Costas Busch - RPI

  2. Answer: Take the DFA that accepts and check if is accepted Membership Question Question: Given regular language and string how can we check if ? Costas Busch - RPI

  3. DFA DFA Costas Busch - RPI

  4. Question: Given regular language how can we check if is empty: ? Answer: Take the DFA that accepts Check if there is any path from the initial state to an accepting state Costas Busch - RPI

  5. DFA DFA Costas Busch - RPI

  6. Question: Given regular language how can we check if is finite? Answer: Take the DFA that accepts Check if there is a walk with cycle from the initial state to a final state Costas Busch - RPI

  7. DFA is infinite DFA is finite Costas Busch - RPI

  8. Answer: Find if Question: Given regular languages and how can we check if ? Costas Busch - RPI

  9. and Costas Busch - RPI

  10. or Costas Busch - RPI

  11. Decidable Problemsof Context-Free Languages Costas Busch - RPI

  12. Parsers Membership Algorithms: • Exhaustive search parser • CYK parsing algorithm Membership Question: for context-free grammar find if string Costas Busch - RPI

  13. Algorithm: • Remove useless variables • Check if start variable is useless Empty Language Question: for context-free grammar find if Costas Busch - RPI

  14. Infinite Language Question: Algorithm: 1. Remove useless variables 2. Remove unit and productions 3. Create dependency graph for variables 4. If there is a loop in the dependency graph then the language is infinite for context-free grammar find if is infinite Costas Busch - RPI

  15. Example: Infinite language Dependency graph Costas Busch - RPI

  16. Costas Busch - RPI

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