In Reverse Mathematics, the axiom system DNR, asserting the existence
of diagonally non-recursive functions, is strictly weaker than
WWKL0 (weak weak König's Lemma).
@article{1102022212,
author = {Ambos-Spies, Klaus and Kjos-Hanssen, Bj\o rn and Lempp, Steffen and Slaman, Theodore A.},
title = {Comparing DNR and WWKL},
journal = {J. Symbolic Logic},
volume = {69},
number = {1},
year = {2004},
pages = { 1089-1104},
language = {en},
url = {http://dml.mathdoc.fr/item/1102022212}
}
Ambos-Spies, Klaus; Kjos-Hanssen, Bjørn; Lempp, Steffen; Slaman, Theodore A. Comparing DNR and WWKL. J. Symbolic Logic, Tome 69 (2004) no. 1, pp. 1089-1104. http://gdmltest.u-ga.fr/item/1102022212/