Thread: prove countable set is measurable?? plz,

plz. help me in that ,,

prove countable setis measurable ???


plz ASAP...

Of course it depends of the measured spaces, for example if you take an uncountable set and the -algebra given by then countable subsets of need not to be measurable.

But if you assume for example that is such that for all , then it's just a consequence of the fact that a -algebra is stable by countable unions.