arXiv · 2603.19946
An order-reversing embedding of Turing degrees into Arthur-Nimue-Merlin degrees
Abstract
The Arthur-Nimue-Merlin degrees are a generalization of the Turing degrees introduced by Kihara as a tangible description of the partially ordered set of Lawvere-Tierney topologies on the effective topos (equivalently, subtoposes of the effective topos). They are defined in terms of a three-player game that introduces both angelic and demonic non-determinism into oracle queries. We construct an order embedding of the Turing degrees with their order reversed into the Arthur-Nimue-Merlin degrees, whose image we call the "co-Turing degrees"; we then study the order relationship of these co-Turing degrees with the (naturally embedded) Turing degrees within the Arthur-Nimue-Merlin degrees.
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Jean Abou Samra, David Alexander Madore. 2026-03-20. An order-reversing embedding of Turing degrees into Arthur-Nimue-Merlin degrees. https://arxiv.org/abs/2603.19946
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