Mathematics – Logic
Scientific paper
2001-05-16
Mathematics
Logic
Scientific paper
Let T be a complete first order theory in a countable relational language L . We assume relation symbols have been added to make each formula equivalent to a predicate. Adjoin a new unary function symbol sigma to obtain the language L_sigma; T_sigma is obtained by adding axioms asserting that sigma is an L-automorphism. We provide necessary and sufficient conditions for T_sigma to have a model companion when T is stable. Namely, we introduce a new condition: T_sigma admits obstructions, and show that T_sigma has a model companion iff and only if T_sigma does not admit obstructions. This condition is weakening of the finite cover property: if a stable theory T has the finite cover property then T_sigma admits obstructions.
Baldwin John
Shelah Saharon
No associations
LandOfFree
Model Companions of T_σfor stable T does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Model Companions of T_σfor stable T, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Model Companions of T_σfor stable T will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-151011