is a domain in and of itself. This indicates that each roof constitutes a discrete domain, and one may carry throughout this entire domain. Granted according to the opinion of Shmuel, this works out well, but according to the opinion of Rav, it is difficult.

The Gemara answers that the Sages of the school of Rav said in the name of Rav: The ruling in the mishna is not a leniency permitting one to carry throughout the entire roof; rather, it is a stringency, ruling that one may not move an object two cubits on this roof and two cubits on that roof. The tanna rules that even the allowance to carry within four cubits is restricted to a single roof.

The Gemara raises a difficulty. But didn’t Rabbi Elazar say: When we were in Babylonia we would say that the Sages of the school of Rav said in the name of Rav: One may move an object on each roof only within four cubits, and those Sages of the school of Shmuel taught a baraita in accordance with their opinion: They have only their own roof.

The Gemara seeks to clarify this baraita. What is the meaning of the statement: They have only their own roof? Is it not that they are permitted to move an object throughout each entire roof? This baraita poses a difficulty to Rav. The Gemara rejects this contention: And is this baraita any stronger a proof than our mishna, which we established as a stringency, that one may not move an object two cubits on this roof and two cubits on that roof? So too, this baraita is teaching that one may not carry two cubits on this roof and two cubits on that roof.

Rav Yosef said, after an illness had caused him to forget his knowledge: I have not heard this halakha of Shmuel’s with regard to roofs. His student Abaye said to him: You yourself said it to us, and it was about this that you said it to us: With regard to a large roof that is adjacent to a small one, carrying on the large one is permitted, as its partitions are distinct where it extends beyond the small one, and carrying on the small one is prohibited, as it is breached along its entire length into the other roof, onto which it is prohibited to carry.

And you said to us about it: Rav Yehuda said that Shmuel said: They only taught this halakha in a case where there are residents on this roof and residents on that roof, as the extended, virtual partition of the small roof is considered a trampled partition. The residents trample this virtual partition as they move from one roof to the other, and the entire length of the small roof is considered breached into the large one.

However, if there are no residents on this roof and none on that one, carrying on both roofs is permitted. Presumably, Shmuel’s reasoning is that in this case the walls of the houses below extend upward and form partitions between the roofs, in accordance with the principle: Extend and raise the partitions.

Rav Yosef said to him: I remember it now. I said to you as follows: They taught this halakha, that carrying is prohibited on the small roof, only with regard to a case where there was an actual partition on all sides of this roof and an actual partition on all sides of that roof, not only between the two roofs. In that case, carrying on the large roof is permitted by means of the remnants of the partition on either side of the opening, and carrying on the small roof is prohibited because it is fully breached into the larger one. However, if there is no partition, neither on all sides of this roof nor on all sides of that roof, carrying on both of them is prohibited.

Abaye raised a difficulty: But didn’t you speak to us of residents? Rav Yosef replied: If I spoke to you of residents, this is what I said to you: They taught this halakha, that carrying is prohibited on the small roof, only in a case where there is an actual partition that renders the area fit for residence on all sides of this roof, and an actual partition that renders the area fit for residence on all sides of that roof, as carrying on the large roof is permitted by means of the remnants of the partition on either side of the opening, and carrying on the small roof is prohibited because it is fully breached into the larger one.

However, if there is a partition that renders the area fit for a residence on all sides of the large roof, but there is no partition that renders the area fit for a residence on the small roof, carrying even on the small roof is permitted for the residents of the large roof. What is the reason for this? Since the residents of the small roof did not erect a partition around their roof, they thereby removed themselves from here and transferred the right to their domain to the residents of the large roof.

This is in accordance with that which Rav Naḥman said: If one affixed a permanent ladder to his roof, while the owners of the neighboring roofs did not do so, it is permitted for him to carry on all the roofs. The failure of the other owners to erect a ladder indicates that they relinquished the right to their roofs to the one who affixed the permanent ladder.

Abaye said: If a person built an upper story atop his house, by surrounding the roof with walls, and erected before its entrance a small partition [dakka] four cubits high that opens to other roofs, it is permitted for him to carry on all the roofs. His construction of the partition is indicative of his plans to utilize the other roofs, while the failure of the other owners to do so indicates that they conceded use of their roofs to him.

Rava said: Sometimes the small partition leads to prohibition. What are the circumstances of this case? It is a case where the partition was erected facing toward the garden of his house and the sides facing the other roofs were sealed. The reason is that through his actions he said