Extension of Embeddings in the Recursively Enumerable Degrees
نویسندگان
چکیده
The extension of embeddings problem for the recursively enumer-able degrees R = (R; <; 0;0 0) asks for given nite partially ordered sets P Q with least and greatest elements, whether every embedding of P into R can be extended to an embedding of Q into R. Many of the landmark theorems giving an algebraic insight into R assert either extension or nonextension of embeddings. We extend, strengthen, and unify these results and their proofs to produce complete and complementary criteria and techniques to analyze instances of extension and nonextension. We conclude that the full extension of embeddings problem is decidable.
منابع مشابه
Lattice Embeddings below a Nonlow2 Recursively Enumerable Degree
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