CS402 GDB fall 2019 Solution Need

[Zari]

GDB Topic 

Theory of automata is study of abstract machines, like Turing Machines, Finite State Machines, Push Down Automata, Mealy and Moore Machines. You have to discuss and explain which kind of automaton machine promisingly can serve as a recognizer for context-free languages.  

 Note:

A concise, coherent and to the point comment is preferred over lengthy comment having irrelevant details. Your comment must not be more than 100 words.

[+ M.Tariq Malik]

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[Mahmood Ahmad]

ha bhai kon c machine best hay to recognize context free languages...??? discuss and why ???

[иαвєєℓ αнмє∂]

CS402 GDB IDEA

Answer

Push Down Automata

Reason

• Context-free languages (CFLs) are generated by context-free grammars. The set of all context-free languages is identical to the set of languages accepted by pushdown automata, and the set of regular languages is a subset of context-free languages.

 

• The language that describes strings that have matching parentheses is a context-free language

 

• Push down automata are non-deterministic finite state machines augmented with additional memory in the form of a stack, which is why the term “push down” is used, as elements are pushed down onto the stack.

https://brilliant.org/wiki/pushdown-automata/

https://brilliant.org/wiki/context-free-languages/

[+ M.Tariq Malik]

CS402 Theory of Automata GDB Solution & Discussion Fall 2019

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CS402 GDB Solution Idea:

 

Turing machine can serve as a recognizer for context free language. Context free languages are described by context free grammars which can be generated by pushdown automata. Regular languages and finite state machines can describe some context free languages but not all. Turing machines can generate all regular languages all context free languages and more.

It shows that the Turning machine will be used. Turning machine is more powerful. Turning machine with an input tape and a working tape can emulate a push down automaton directly using the same number of steps. Turning machines can accept some non context free languages as well, in addition to context free languages.

A finite state machine cannot identify or recognize context free language at all. Push down automata and turning machine both can identify context free language but a turning machine can recognize context free language using few states or transition than a push down automata for the same language.

[+ M.Tariq Malik]

Another solution idea of CS402 GDB:

 

A finite state machine cannot identify or recognize Context free language at all. Push down automata (PDA) and Turing machine both can identify/recognize Context free language but a Turing machine can recognize context free language using few states or transition than a push down automata for the same language.

Turing machine is more powerful, Turing machine with an input tape and a working tape can emulate a pushdown automaton directly, using the same number of steps. Turing machines can accept some non- Context free languages as well, in addition to Context free languages.