Lattice nonembeddings and initial segments of the recursively enumerable degrees
The structure of an arbitrary initial segment of the upper semilattice of r.e. degrees is investigated. Main result: There exists a nonzero r.e. degree that bounds no critical triple. Conjecture: Every lattice that contains no critical triple is embeddable below every nonzero r.e. degree.
initial segment of the upper semilattice of r.e. degrees
scientific article; zbMATH DE number 4191613
scientific article