User blog comment:PolyhedralMatrix102/Question about Cardinals/@comment-11227630-20180317041140/@comment-35018170-20180317135950

good. but what is "cofinality"? do you mean cofinality as in, \(\aleph_3\) has cofinality 3, or \(\aleph_{\omega}\) has cofinality \(\omega\), or another meaning?

also, if \(\aleph_1\) doesn't necessarily equal \(2^{\aleph_0}\) because of something called the continuum hypo. then isn't the question of whether \(\aleph_1\)'s a "strong limit cardinal" undecidable?