Journal of Mathematical Logic ( IF 0.9 ) Pub Date : 2023-08-11 , DOI: 10.1142/s0219061324500028 Barbara F. Csima 1 , Dino Rossegger 2, 3
In this paper, we give a characterization of the strong degrees of categoricity of computable structures greater or equal to . They are precisely the treeable degrees — the least degrees of paths through computable trees — that compute . As a corollary, we obtain several new examples of degrees of categoricity. Among them we show that every degree with for a computable ordinal greater than is the strong degree of categoricity of a rigid structure. Using quite different techniques we show that every degree with is the strong degree of categoricity of a structure. Together with the above example this answers a question of Csima and Ng. To complete the picture we show that there is a degree with that is not the degree of categoricity of a rigid structure.
中文翻译:
分类度和可树度
在本文中,我们给出了可计算结构的强范畴度的表征,大于或等于。它们正是可树度——通过可计算树的路径的最小度——计算。作为推论,我们获得了几个新的类别度示例。其中我们表明每个度和为了可计算序数大于是刚性结构的强范畴化程度。使用完全不同的技术,我们表明每个学位和是结构的强范畴化程度。结合上面的例子,这就回答了 Csima 和 Ng 的问题。为了完成图片,我们表明有一个学位和这不是刚性结构的范畴化程度。