Assuming one is inside an eruv which generally permits transferring between domains on Shabbat, may one use an umbrella on Shabbat? If not, why not? Follow-up question: What about other things that ...
According to Rabbi Dovid Ostroff Shlita The Rama in Hilchos Succah 626:3 says that one is permitted to open and shut hinged flaps that are used for covering the Succah when raining. The ...