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Odifreddi asked, as Problem 3 in his surveys "Strong Reducibilities" (1981) and "Reducibilities" (1999), whether every computably enumerable tttt-degree contains a c.e. irreducible mm-degree, meaning an mm-degree consisting of a single 11-degree. Answered negatively: there is a c.e. tttt-degree containing no c.e. irreducible mm-degree. This also shows Jockusch's 1969 theorem, which produces an irreducible mm-degree inside every c.e. tttt-degree, is strictly optimal and cannot be strengthened to make that degree c.e.

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No person has examined this. Nothing here has been checked at all. say whether it holds →

  1. proof attempt · #1

    Patrizio Cintioli, using Gemini Deep Think

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    ai co developed
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    Credited at the level of the paper rather than the lemma. The author describes the work as the result of an extended human-AI interaction in which several structural ideas and technical arguments emerged from exploratory sessions with Gemini Deep Think, after which he fully reworked and verified all arguments and takes sole responsibility for their correctness. Nothing is attributed step by step, so the contribution is real but unitemised.

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