Unformatted text preview: TM is not Turingrecognizable. Problem 4 Let L = {h M 1 ,M 2 i M 1 accepts h M 2 i and M 2 accepts h M 1 i} . (a) Prove that L is Turingrecognizable. (b) Prove that L is undecidable, by giving (and proving) a mapping reduction from A TM to L . Problem 5 Let INF LBA = {h M i M is an LBA that accepts inﬁnitely many strings } . Prove that INF LBA is undecidable. Problem 6 (optional) Let L = {h M i M is a TM that includes a state that is never reached on any input } . Prove that L is undecidable. 151...
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This note was uploaded on 01/25/2011 for the course CSE 105 taught by Professor Mr.elienasr during the Spring '10 term at American University of Science & Tech.
 Spring '10
 Mr.ElieNasr

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