投射理想上的弱Rudin-Keisler约化
Weak Rudin-Keisler reductions on projective ideals
摘要：
我们考虑一个稍微修改的形式的标准Rudin-Keisler为了理想和证明存在的完整的（关于这个顺序）理想在各种投射类。使用我们的方法，我们得到了一个简单的证明Hjorth定理的存在一个完整的$\mathbf Π^1_1$等价关系。我们对Hjorth定理的证明使我们（在PD下）能够将他的结果推广到$\mathbf Π^1_{2n+1}$等价关系的类。
英文摘要：
We consider a slightly modified form of the standard Rudin-Keisler order on ideals and demonstrate the existence of complete (with respect to this order) ideals in various projective classes. Using our methods, we obtain a simple proof of Hjorth's theorem on the existence of a complete $\mathbf Π^1_1$ equivalence relation. Our proof of Hjorth's theorem enables us (under PD) to generalize his result to the classes of $\mathbf Π^1_{2n+1}$ equivalence relations.
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