On the Π2-completeness of Contextual Equivalence
نویسنده
چکیده
In this note, we present a proof of Π2-completeness of contextual equivalence of Turing machines via a reduction of the language FIN to contextual inequivalence. FIN is the language of encodings 〈Mi〉 of Turing machines Mi for which the set Wi of inputs on which Mi halts (or the set of accepting inputs of Mi) is finite. FIN is known to be Σ 0 2-complete.
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