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Complete, Recursively Enumerable Relations in Arithmetic

✍ Scribed by Giovanna D'Agostino; Mario Magnago


Publisher
John Wiley and Sons
Year
1995
Tongue
English
Weight
489 KB
Volume
41
Category
Article
ISSN
0044-3050

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✦ Synopsis


Abstract

Using only propositional connectives and the provability predicate of a Ξ£~1~‐sound theory T containing Peano Arithmetic we define recursively enumerable relations that are complete for specific natural classes of relations, as the class of all r. e. relations, and the class of all strict partial orders. We apply these results to give representations of these classes in T by means of formulas.


πŸ“œ SIMILAR VOLUMES


Relatively Recursively Enumerable Versus
✍ Grzegorz Michalski πŸ“‚ Article πŸ“… 1995 πŸ› John Wiley and Sons 🌐 English βš– 416 KB

## Abstract We show that that every countable model of __PA__ has a conservative extension __M__ with a subset __Y__ such that a certain Ξ£~1~(__Y__)‐formula defines in __M__ a subset which is not r. e. relative to __Y__.

The Index Set of Injectively Enumerable
✍ Stephan Wehner πŸ“‚ Article πŸ“… 1994 πŸ› John Wiley and Sons 🌐 English βš– 372 KB

## Abstract I introduce an effective enumeration of all effective enumerations of classes of r. e. sets and define with this the index set __IE__ of injectively enumerable classes. It is easy to see that this set is βˆ‘~5~ in the Arithmetical Hierarchy and I describe a proof for the βˆ‘~5~‐hardness of

The Recursively Mahlo Property in Second
✍ Michael Rathjen πŸ“‚ Article πŸ“… 1996 πŸ› John Wiley and Sons 🌐 English βš– 388 KB

## Abstract The paper characterizes the second order arithmetic theorems of a set theory that features a recursively Mahlo universe; thereby complementing prior proof‐theoretic investigations on this notion. It is shown that the property of being recursively Mahlo corresponds to a certain kind of Ξ²