An Abelian group G is strongly -free i G is L ∞; -equivalent to a free Abelian group i the isomorphism player has a winning strategy in an Ehrenfeucht-Fra ssà e game of length ! between G and a free Abelian group. We study possible longer Ehrenfeucht-Fra ssà e games between a nonfree group and a fre
Trees and Ehrenfeucht–Fraı̈ssé games
✍ Scribed by Stevo Todorčević; Jouko Väänänen
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 221 KB
- Volume
- 100
- Category
- Article
- ISSN
- 0168-0072
No coin nor oath required. For personal study only.
✦ Synopsis
Trees are natural generalizations of ordinals and this is especially apparent when one tries to ÿnd an uncountable analogue of the concept of the Scott-rank of a countable structure. The purpose of this paper is to introduce new methods in the study of an ordering between trees whose analogue is the usual ordering between ordinals. For example, one of the methods is the tree-analogue of the successor operation on the ordinals.
📜 SIMILAR VOLUMES
This paper introduces a new Ehrenfeucht-Fraïssé type game that is played on two classes of models rather than just two models. This game extends and generalizes the known Ajtai-Fagin game to the case when there are several alternating (coloring) moves played in different models. The game allows Dupl
## Abstract In this paper we prove under some set theoretical assumptions that if __T__ is a countable unstable theory then there is a pair of models of __T__ such that Ehrenfeucht‐Fraïssé games between these models of large variety of lengths are non‐determined.