Chapter 7, Mishna 5, 6
May we establish a merging of alleyways without conveying possession of the food (used in the eruv) to all residents who benefit from the eruv? To understand the principle involved, we examine an incident in which a mother-in-law sought to join Shabbos boundaries on behalf of her daughter-in-law, who was delayed in returning from a bath house outside her Shabbos boundary until after darkness fell on Friday night. Rabbi Hiyya said the eruv was not valid and the young woman was prohibited to return because her mother-in-law did not first convey possession of the food to her (via an agent). Rabbi Yishmael strongly objected, and may have carried the day. Possession is a different issue than awareness, which is normally required for eruvei techumin, but may not have been required in this case because of the young woman’s established intent to return. How much food is required for a merging of alleyways? What happens when the required amount is diminished on Shabbos?