Give examples of when each of the following are useful?
a) regular language
b)context free language
c)np-completeness
d)decidability

Explanation:

a . Regular language -

Uses are as follows -

matching the regular expression patterns , like the Unix grep  .patterns search and replace operations . programming languages for the Lexical analysis in the compilation phase .

b. Context Free Language -

Uses are as follows -

match the count of one symbol with another symbol  .Match a symbol with another symbol  .submit one symbol with string made of other symbols recursively .

c. NP-Completeness  -

Uses are as follows -

used for Weighted Model Counting Used for Integer Programming used for Boolean Satisfiability testing

d. Decidability -

Uses are as follows -

Team games with incomplete information are undecidable. Infinite chess (with limitations on rules and game pieces) is decidable. Chess is decidable game

The awnser is d. i just looked it up 

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