Eiruvin 6:8-9

Eiruvin 6:8

If five courtyards open one into the next and they all open to an alleyway, and the residents of each courtyard made their own eiruvs but they did not make a shittuf (partnership) to combine the courtyards, then they may carry in the courtyards but not in the alley. If they also made a shittuf, they may carry both in the courtyards and in the alley. If they made eiruvs in their courtyards and a shittuf for the alley but one of the residents neglected to contribute towards his courtyard’s eiruv (but he still participated in the shittuf), they may still carry in both places. If a resident of the alley neglected to participate in the shittuf, they may carry in their courtyards but not in the alley. This is because the relationship of courtyards to alleys is the same as houses to courtyards. (That is, the smaller units make up the larger units and must be “combined” through the appropriate means. Failure to do so impedes the residents’ ability to carry there on Shabbos.)

Eiruvin 6:9

If there were two courtyards, one inside the other, and only the inner one made an eiruv, they may carry but the residents of the outer courtyard may not. If only the outer courtyard made an eiruv, neither may carry. (The inner residents may not carry because they did not make an eiruv; the outer residents may not carry because the inner residents also have right of way through their courtyard.) If each made an eiruv, the residents may carry in their own courtyards (but not between them). Rabbi Akiva still prohibits the outer courtyard because of the inner residents’ right of way but the Sages permit it, maintaining that right of way is not an impediment.