1. People in a Chatzer who made an Eruv may not nullify their domain in the Chatzer to the two people who did not.
2. There is a dispute about whether nullification must be done with everyone in the Chatzer or with only one person.
3. The Gemara discusses whether a person who inherits his father's domain on Shabbos may nullify his portion in the Chatzer.
4. Beraisa: Whatever was permitted (regarding Eruv) at the beginning of Shabbos is permitted for all of Shabbos.
5. Beraisa: Whatever was forbidden (regarding Eruv) at the beginning of Shabbos is forbidden for all of Shabbos.
A BIT MORE
1. This applies even if they say to one of those who did not make an Eruv, "We nullify our share in the Chatzer to you in order that you should nullify both our and your share to the second person."
2. Rabah: One must nullify his domain with everyone in the Chatzer. Abaye: He must nullify only to one person.
3. Rav Nachman says that he may nullify his inherited domain, while the members of the academy of Shmuel say that he may not.
4. The Gemara explains that this refers to a case where the inhabitants of two courtyards made an Eruv together based on a window or door between them that was later closed during Shabbos. The Eruv is still deemed valid for the rest of Shabbos.
5. The Gemara says that this refers to two houses on opposite sides of the public domain that were surrounded by Nochrim on Shabbos. Since they were not allowed to carry when Shabbos entered, they may not carry even after the area between them became in effect one courtyard (as a result of being surrounded by Nochrim).