# Measures beyond Lebesgue: are Solovay's proofs extendible to them?

1. Mar 15, 2013

In 1970, Solovay proved that,
although
(1) under the assumptions of ZF & "there exists a real-valued measurable cardinal", one could construct a measure μ (specifically, a countably additive extension of Lebesgue measure) such that all sets of real numbers were measurable (wrt μ),
nonetheless
(2) under the assumption of ZFC, one can construct a set (e.g., the Vitali set) which is not Lebesgue measurable.

However, I am not sure whether these proofs carry over to all measures: in other words, is it conceivable that, under ZFC & a sufficiently strong large cardinal axiom, there is a measure M so that all sets of real numbers are measurable wrt M? (For example, it would seem reasonable that the Vitali set is also not measurable by the μ in (1), but what of other measures?)

2. Mar 15, 2013

### mathman

I am not familiar with the work you are discussing. However with a measure, where each point has measure 1, all sets are measurable.

3. Mar 15, 2013

### pwsnafu

The trivial measure (sends every set to zero) does the job.

If you want non-trivial example consider the Dirac measure.

4. Mar 17, 2013