A model is presented in which the equivalence relation xCy iff L[x]=L[y] of equiconstructibility of reals does not admit a reasonable form of the Glimm-Effros theorem. The model is a kind of iterated Sacks generic extension of the constructible model, but with an “ill“founded “length” of the iteration. In another model of this type, we get an example of a non-Glimm-Effros equivalence relation on reals. As a more elementary application of the technique of “ill“founded Sacks iterations, we obtain a model in which every nonconstructible real codes a collapse of a given cardinal to .
@article{bwmeta1.element.bwnjournal-article-fmv154i1p1bwm, author = {Vladimir Kanovei}, title = {Non-Glimm--Effros equivalence relations at second projective level}, journal = {Fundamenta Mathematicae}, volume = {154}, year = {1997}, pages = {1-35}, zbl = {0883.03034}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-fmv154i1p1bwm} }
Kanovei, Vladimir. Non-Glimm–Effros equivalence relations at second projective level. Fundamenta Mathematicae, Tome 154 (1997) pp. 1-35. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-fmv154i1p1bwm/
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