4 papers · 1 filter
A Borel graphable equivalence relation with no Borel graphing of diameter two
Patrick Lutz
We answer a question of Arant, Kechris and Lutz by showing that there is a Borel graphable equivalence relation with no Borel graphing of diameter less than 3. More specifically, w…
Ranking theories via encoded -models
Hanul Jeon, Patrick Lutz, Fedor Pakhomov +1
Ranking theories according to their strength is a recurring motif in mathematical logic. We introduce a new ranking of arbitrary (not necessarily recursively axiomatized) theories…
Conway and Doyle Can Divide by Three, But I Can't
Patrick Lutz
Conway and Doyle have claimed to be able to divide by three. We attempt to replicate their achievement and fail. In the process, we get tangled up in some shoes and socks and forge…
A theory satisfying a strong version of Tennenbaum's theorem
Patrick Lutz, James Walsh
We answer a question of Pakhomov by showing that there is a consistent, c.e. theory such that no theory which is definitionally equivalent to has a computable model. A key…