T \subseteq ds(α)上的一致n位函数
Uniform n-place functions on T\subseteq ds(α)
摘要:
本文将Erdos-Rado定理推广到良基树类。我们定义了类rs(infty)^{< aleph_0}(序数递减序列的有限序列)与aleph_0等价类的等价关系,并对n< omega定义了rs(infty)^{< aleph_0}的mu色着色的n端一致性概念.然后我们证明了对于每个序数alpha,n< omega和基数mu,存在一个序数lambda,使得对于T=rs(lambda)^{< aleph_0}的任何带有mu颜色的着色c,T包含与rs(alpha)同构的S,使得c rest S^{< aleph_0}是n端一致的。对于定义域T^n的c,这等价于找到同构于rs(alpha)的S子集T,使得c upharpoonright S^{n}仅依赖于所定义关系的等价类,因此特别是T->(rs(alpha))^ n_{mu, aleph_0}。我们还得出了一个结论,着色的n-元组从一个分散的线性秩序。
英文摘要:
In this paper the Erdos-Rado theorem is generalized to the class of well founded trees. We define an equivalence relation on the class rs(infty)^{< aleph_0} (finite sequences of decreasing sequences of ordinals) with aleph_0 equivalence classes, and for n< omega a notion of n-end-uniformity for a colouring of rs(infty)^{< aleph_0} with mu colours. We then show that for every ordinal alpha, n< omega and cardinal mu there is an ordinal lambda so that for any colouring c of T=rs(lambda)^{< aleph_0} with mu colours, T contains S isomorphic to rs(alpha) so that c rest S^{< aleph_0} is n-end uniform. For c with domain T^n this is equivalent to finding S subseteq T isomorphic to rs(alpha) so that c upharpoonright S^{n} depends only on the equivalence class of the defined relation, so in particular T-> (rs(alpha))^n_{mu, aleph_0} . We also draw a conclusion on colourings of n-tuples from a scattered linear order.
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