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Michael Sipser Edition 3 Exercise 5 Question 2 (Page No. 239)
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Show that $EQ_{CFG}$ is coTuringrecognizable.
michaelsipser
theoryofcomputation
contextfreegrammars
turingrecognizablelanguages
proof
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Oct 18, 2019
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Theory of Computation
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Lakshman Patel RJIT

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Michael Sipser Edition 3 Exercise 5 Question 36 (Page No. 242)
Say that a $CFG$ is minimal if none of its rules can be removed without changing the language generated. Let $MIN_{CFG} = \{\langle G \rangle \mid \text{G is a minimal CFG}\}$. Show that $MIN_{CFG}$ is $T$recognizable. Show that $MIN_{CFG}$ is undecidable.
asked
Oct 20, 2019
in
Theory of Computation
by
Lakshman Patel RJIT

159
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michaelsipser
theoryofcomputation
contextfreegrammars
turingrecognizablelanguages
decidability
proof
0
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0
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2
Michael Sipser Edition 3 Exercise 5 Question 7 (Page No. 239)
Show that if $A$ is Turingrecognizable and $A\leq_{m} \overline{A},$ then $A$ is decidable.
asked
Oct 19, 2019
in
Theory of Computation
by
Lakshman Patel RJIT

26
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michaelsipser
theoryofcomputation
turingrecognizablelanguages
decidability
reduction
proof
0
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0
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3
Michael Sipser Edition 3 Exercise 5 Question 1 (Page No. 239)
Show that $EQ_{CFG}$ is undecidable.
asked
Oct 18, 2019
in
Theory of Computation
by
Lakshman Patel RJIT

17
views
michaelsipser
theoryofcomputation
contextfreegrammars
decidability
proof
+1
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0
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4
Michael Sipser Edition 3 Exercise 5 Question 35 (Page No. 242)
Say that a variable $A$ in $CFG \:G$ is necessary if it appears in every derivation of some string $w \in G$. Let $NECESSARY_{CFG} = \{\langle G, A\rangle \mid \text{A is a necessary variable in G}\}$. Show that $NECESSARY_{CFG}$ is Turingrecognizable. Show that $NECESSARY_{CFG} $is undecidable.
asked
Oct 20, 2019
in
Theory of Computation
by
Lakshman Patel RJIT

62
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michaelsipser
theoryofcomputation
turingrecognizablelanguages
decidability
proof
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