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• CommentRowNumber1.
• CommentAuthorDavidRoberts
• CommentTimeDec 22nd 2011

Theorem: The existence of arbitrarily large supercompact cardinals implies the statement:

Every absolute epireflective class of objects in a balanced accessible category is a small-orthogonality class.

In other words, if $L$ is a reflective localization functor on a balanced accessible category such that the unit morphism $X \to L X$ is an epimorphism for all $X$ and the class of $L$-local objects is defined by an absolute formula, then the existence of a suficciently large supercompact cardinal implies that $L$ is a localization with respect to some set of morphisms.

This is in BagariaCasacubertaMathias

Urs Schreiber: I am being told in prvivate communication that the assumption of epis can actually be dropped. A refined result is due out soon.