Countable products and countable sums of compact metrizable spaces in the absence of the Axiom of Choice

Abstract

The main aim of the article is to show, in the absence of the Axiom of Choice, relationships between the following, independent of $\mathbf{ZF}$, statements: "Every countable product of compact metrizable spaces is separable (respectively, compact)" and "Every countable product of compact metrizable spaces is metrizable". Statements related to the above-mentioned ones are also studied. Permutation models (among them new ones) are shown in which a countable sum (also a countable product) of metrizable spaces need not be metrizable, countable unions of countable sets are countable and there is a countable family of non-empty sets of size at most $2^{{\aleph }_0}$ which does not have a choice function. A new permutation model is constructed in which every uncountable compact metrizable space is of size at least $2^{{\aleph }_0}$ but a denumerable family of denumerable sets need not have a multiple choice function.