2016/09/09 by Boney, Will
#FOS: Mathematics #Logic (math.LO)
paper · doi:10.48550/arxiv.1609.02970
We develop the notion of coherent ultrafilters (extenders without normality or well-foundedness). We then use definable coherent ultraproducts to characterize any extension of a model M in any fragment of \mathbbL∞, ω that defines Skolem functions by a sufficiently complete (but in ZFC) coherent ultrafilter. We apply this method to various elementary classes and AECs.