Contiguity and Distributivity in the Enumerable Turing Degrees

Downey, Rodney G.; Lempp, Steffen

J. Symbolic Logic, Tome 62 (1997) no. 1, p. 1215-1240 / Harvested from Project Euclid

Résumé

We prove that a (recursively) enumerable degree is contiguous iff it is locally distributive. This settles a twenty-year old question going back to Ladner and Sasso. We also prove that strong contiguity and contiguity coincide, settling a question of the first author, and prove that no $m$-topped degree is contiguous, settling a question of the first author and Carl Jockusch [11]. Finally, we prove some results concerning local distributivity and relativized weak truth table reducibility.

Publié le : 1997-12-14
Classification:

@article{1183745378,
     author = {Downey, Rodney G. and Lempp, Steffen},
     title = {Contiguity and Distributivity in the Enumerable Turing Degrees},
     journal = {J. Symbolic Logic},
     volume = {62},
     number = {1},
     year = {1997},
     pages = { 1215-1240},
     language = {en},
     url = {http://dml.mathdoc.fr/item/1183745378}
}

Downey, Rodney G.; Lempp, Steffen. Contiguity and Distributivity in the Enumerable Turing Degrees. J. Symbolic Logic, Tome 62 (1997) no. 1, pp.  1215-1240. http://gdmltest.u-ga.fr/item/1183745378/