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Jul 17, 2020 at 3:29 comment added Haim @TimothyChow It seems to me like an almost empirical fact that in order for a non-set theoretic statement to be susceptible to set theoretic methods, it should either be a statement involving subsets of Polish spaces with a very simple (Borel/analytic) definition (in which case methods from DST can be used) or it shouldn't be absolute (so forcing, large cardinals and inner models might be useful). It seems that non-set theoretic statements that satisfy either of the above requirements are harder to come by, whereas such requirements don't exist in the case of model theoretic applications.
Jul 17, 2020 at 1:50 comment added Timothy Chow At the risk of stating the obvious: Sets have no structure. Models have structure. It shouldn't be too surprising that they would have applications to different kinds of questions, should it?
Jul 16, 2020 at 19:14 comment added Haim Dynamics is another example of an area where both set theory and model theory have many applications (again, I don't know which of them satisfy your criterion for being deep), one recent example is this paper by Hrushovski, that makes an interesting connection to the Kechris-Pestov-Todorcevic correspondence: arxiv.org/pdf/1911.01129.pdf
Jul 16, 2020 at 17:35 comment added Haim @MohammadGolshani What would qualify as a "deep application"?
Jul 16, 2020 at 16:56 comment added Mohammad Golshani I am essentially looking for a part of mathematics outside of logic (say not a theory), where both set theory and model theory have deep applications.
Jul 16, 2020 at 16:54 comment added Mohammad Golshani @Haim Yes I know that, even for example I can say Shelah's proof of independence of Ax-Kochen isomorphism theorem from CH vs. the model theoretic works on the subject. But if for example you look at the paper you sent, I think you agree that the subjects of the applications are different from what set theory has, also I think the applications stated are not as deep as those given by set theory.
Jul 16, 2020 at 15:59 comment added Haim I'm not sure that your observation is correct. For example, in addition to the applications of set theory to $C^*$-algebras, there are also many applications of model theory to the field: arxiv.org/pdf/1602.08072.pdf
Jul 16, 2020 at 13:15 comment added nombre Related to your second remark: I would say model theory is mostly about first order statements, whereas non elementary set theory deals with higher order statements.
Jul 16, 2020 at 7:48 history asked Mohammad Golshani CC BY-SA 4.0