On Fraïssé's conjecture for linear orders of finite Hausdorff rank
نویسندگان
چکیده
We prove that the maximal order type of the wqo of linear orders of finite Hausdorff rank under embeddability is φ2(0), the first fixed point of the ε-function. We then show that Fräıssé’s conjecture restricted to linear orders of finite Hausdorff rank is provable in ACA0 + “φ2(0) is well-ordered” and, over RCA0, implies ACA ′ 0 + “φ2(0) is well-ordered”.
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ورودعنوان ژورنال:
- Ann. Pure Appl. Logic
دوره 160 شماره
صفحات -
تاریخ انتشار 2009