[FOM] CH and forcing
Andreas Blass
ablass at umich.edu
Mon Jul 4 12:39:05 EDT 2011
Roger Bishop Jones asked about the assertion
> "Every model of ZFC has a forcing extension in which CH
> fails."
>
In this context, I would interpret "forcing extension" to mean a
Boolean-valued model. With this interpretation, the assertion is correct.
If one insists on two-valued models, the assertion is still correct,
provided one does not require models to be well-founded. One can get a
two-valued model as the quotient of a Boolean-valued model by any
ultrafilter (not necessarily generic).
If, however, one wants two-valued, well-founded (or, equivalently,
transitive) models, then there is indeed a problem when the given model is
uncountable.
Andreas Blass
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