Coding with ladders a well-ordering of the reals
Logic
2007-05-23 v1
Abstract
Any model of ZFC + GCH has a generic extension (made with a poset of size aleph_2) in which the following hold: MA + 2^{aleph_0}= aleph_2+ there exists a Delta^2_1-well ordering of the reals. The proof consists in iterating posets designed to change at will the guessing properties of ladder systems on omega_1. Therefore, the study of such ladders is a main concern of this article.
Cite
@article{arxiv.math/0104195,
title = {Coding with ladders a well-ordering of the reals},
author = {Uri Abraham and Saharon Shelah},
journal= {arXiv preprint arXiv:math/0104195},
year = {2007}
}