74 citations · 433 across the 68 of their papers we have counts for
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math.LO2009★ 3 cited
A dichotomy for the number of ultrapowers
Ilijas Farah, Saharon Shelah
We prove a strong dichotomy for the number of ultrapowers of a given countable model associated with nonprincipal ultrafilters on N. They are either all isomorphic, or else there a…
math.LO2009★ 5 cited
Orthonormal bases of Hilbert spaces
Ilijas Farah
I prove that a Hilbert space has the property that each of its dense (not necessarily closed) subspaces contains an orthoormal basis if and only if it is separable.