Do the restrictions for the three weeks (music, haircuts, shaving, etc.) begin by sundown before the fast (17 Tammuz), or at the start of the fast (morning of 17 Tammuz)?
When do the restrictions of 3 weeks start when 17 Tammuz is on Shabbos (e.g. this year)? Do they start motzei shabbos (already 18 Tammuz), since the 17 Tammuz is technically on shabbos or do they ...
May one swim on Shiva Asar B"Tamuz? If not, why not? (sources)