The countable-index conjecture for automatic continuity in Polish groups

Let GG be a Polish group. Say that GG has the countable index property when every subgroup of index at most countable is open, and say that GG has the automatic continuity property when every homomorphism from GG into a separable topological group is continuous. Countable-index conjecture. Every Polish group with the countable index property also has the automatic continuity property. The conjecture asks whether the countable index and automatic continuity properties coincide for Polish groups; the source gives no resolution.

Sources & referencesView supporting material

Primary source

Christian Rosendal and Luis Carlos Suarez, “Aspects of automatic continuity”, arXiv:2406.12143 (2025).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.