\b[N.] A larger model may collapse a singular <cardinal number>, destroying cardinalhood, so the assertion is not described by an <upward absolute formula>. It may instead add a short <cofinal function> to a <regular cardinal> in the smaller model, so it is not described by a <downward absolute formula>. This is the <nonabsoluteness of singular cardinalhood>.

Solution

Past exam of the mathematics course of the University of Cambridge / 2019 / iii / Paper 121 / 1 / i / f / Solution

 Solution (source code)