Chapter 3, Mishna 4, 5, 6 Eruv in a pit, Shabbos dwelling in a karmelis (neither private nor public domain – carrying into or out prohibited on Shabbos by rabbinic decree) is valid according to Rebbi. Eruv on a tall reed valid if the reed has been cut and reinserted into ground. This law turns on whether the reed is a tree OR concern that we’ll cut it accidentally on Shabbos if we make use of it (violating the reaping prohibition), even if it is not a tree. Incident in Neharde’a when army commandeered the study hall. Eruv in a locked cupboard and key is lost is still valid. But owner has no access to his eruv on Shabbos! Could be that it’s a mortar-free, brick cupboard and we can break into it. Could be that it was created for a festival, but a related Tosefta shows that we are in fact talking about Shabbos. So why is this eruv valid? Tune in tomorrow!