Automatic continuity for homomorphisms into free products
arXiv:1212.1596
Abstract
A homomorphism from a completely metrizable topological group into a free product of groups whose image is not contained in a factor of the free product is shown to be continuous with respect to the discrete topology on the range. In particular, any completely metrizable group topology on a free product is discrete.
15 pages, 1 table. Final version. To appear in the Journal of Symbolic Logic