Unformatted text preview: recursive set? an r.e. set? not r.e.? Give short proofs of your answers. You may use any theorem proved in class. 6. Consider a reduction of problem A to problem B. What is the most precise claim you can make about problem B for each of the following situations? a) A is NPcomplete and the reduction is in polynomial time. b) A is in polynomial time and the reduction is also in polynomial time. c) A is NPcomplete and the reduction is in Pspace. d) A is in nondeterministic polynomial time and the reduction is in polynomial time. e) A requires exponential time and the reduction is in polynomial time. f) A is Pspace complete and the reduction is in Pspace. 7. What is a quantified Boolean formula? (Ten words or less) Given an algorithm for deciding if a QBF is true. Is the QBF problem in P?, NP?, Pspace?...
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 Spring '07
 HOPCROFT
 Computational complexity theory, Formal language, Formal languages, PSPACE, polynomial time, contextfree language

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