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\title{\vspace{-3ex}\bf Mapping Reductions\\[2ex]
\rm\normalsize CS 311, Fall 2015}
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\paragraph{Exercise 1}
Use a reduction to show that the language $CFL_{TM}$ is undecidable.
\[CFL_{TM} = \{ \langle M \rangle \;|\; M \mbox{ is a $TM$ and $L(M)$ is context free}\} \]

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