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In this paper, we study Ramsey-type Konig's Lemma, written RWKL, using a technique introduced by Lerman, Solomon, and the second author. This technique uses iterated forcing to construct an omega-model satisfying one principle T_1 but not another T_2. The technique often allows one to translate a "one step" construction (building an instance of T_2 along with a collection of solutions to each computable instance of T_1) into an omega-model separation (building a computable instance of T_2 together with a Turing ideal where T_1 holds). We illustrate this translation by separating d-DNR from DNR (reproving a result of Ambos-Spies, Kjos-Hanssen, Lempp, and Slaman), and then apply this technique to separate RWKL from DNR (which has been shown separately by Bienvenu, Patey, and Schafer).

@article{flood14:separating_principles_below_wkl0, author = {{Flood}, S. and {Towsner}, H.}, title = "{Separating Principles Below WKL0}", journal={Mathematical Logic Quarterly}, year={2016}, month=dec, volume = {62}, number = {6}, issn = {1521-3870}, urljournal = {http://dx.doi.org/10.1002/malq.201500001}, doi = {10.1002/malq.201500001}, pages = {507--529}, urlarxiv={http://arxiv.org/abs/1410.4068}, abstract={In this paper, we study Ramsey-type Konig's Lemma, written RWKL, using a technique introduced by Lerman, Solomon, and the second author. This technique uses iterated forcing to construct an omega-model satisfying one principle T_1 but not another T_2. The technique often allows one to translate a "one step" construction (building an instance of T_2 along with a collection of solutions to each computable instance of T_1) into an omega-model separation (building a computable instance of T_2 together with a Turing ideal where T_1 holds). We illustrate this translation by separating d-DNR from DNR (reproving a result of Ambos-Spies, Kjos-Hanssen, Lempp, and Slaman), and then apply this technique to separate RWKL from DNR (which has been shown separately by Bienvenu, Patey, and Schafer). } }

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