if its protrusion is less than four cubits, it is deemed a side post that renders it permitted to carry in the alleyway, and no other side post is required to render it permitted. However, if it protrudes four cubits, that section is deemed an alleyway, and another side post is required to render it permitted to carry in it.

The Gemara poses a question: That side post, which is added in order to permit carrying within the alleyway that was formed by the four-cubit side post, where does one position it such that one may carry within the alleyway? The Gemara clarifies its difficulty: If one positions it alongside the first side post as an addition to it, it looks as if he is merely extending the original side post, and it is not noticeable that an extra side post is present.

Rav Pappa said: He should position it, the extra side post, on the other side of the alleyway, near the opposite wall. Rav Huna, son of Rav Yehoshua, said: Even if you say that he positions it alongside the first side post, it is valid, so long as he adds to it or diminishes from it in thickness or height, so that it will be noticeable that it is a side post of its own.

The Gemara limits the application of Rami bar Ḥama’s ruling: Rav Huna, son of Rav Yehoshua, said: We stated this halakha with regard to a side post protruding four cubits into the alleyway only in the case of an alleyway that is at least eight cubits wide. However, in the case of an alleyway that is only seven cubits wide, it is permitted to carry within the alleyway without an additional side post, not because the original side post functions as a side post but rather because it sufficiently seals off the entrance to the alleyway such that the standing segment is greater than the breached segment. The alleyway is now closed off from all four sides, and the remaining opening to the public domain is regarded as an entrance, as most of that side is closed and only a small part of it is open.

And this is derived by means of an a fortiori inference from a courtyard: Just as in a courtyard, which is not rendered a permitted domain by means of a side post or a cross beam, but actual partitions are required, it is nevertheless rendered a permitted domain even if there are gaps in the partitions, as long as the standing segment is greater than the breached segment in an alleyway, with regard to which the Sages were lenient, as it is rendered a permitted domain by means of a side post or a cross beam, is it not right that it is rendered a permitted domain when the standing segment of the partition is greater than the breached segment?

The Gemara refutes this a fortiori inference that was based on the fact that the legal status of a courtyard is more lenient than that of an alleyway, as it is in fact more stringent than that of an alleyway in at least one respect. With regard to what is true of a courtyard, that as long as its breach is less than ten cubits it remains a permitted domain, can you say the same of an alleyway, which is more stringent, as in a case where its breach is only four handbreadths it is not permitted to carry in the alleyway? Therefore, the halakha of an alleyway cannot be derived from the halakha of a courtyard.

The Gemara answers: Rav Huna, son of Rav Yehoshua, holds that the breach of an alleyway is also ten cubits. The Gemara raises a difficulty: But in accordance with whose opinion did we state this a fortiori inference? It is in accordance with the opinion of Rav Huna. But doesn’t Rav Huna himself hold that the breach of an alleyway is four handbreadths.

The Gemara answers: Rav Huna, son of Rav Yehoshua, did not come to explain Rav Huna’s position. Rather, he stated his own view, and he does not accept Rav Huna’s opinion with regard to the law of a breach in an alleyway.

Rav Ashi went further than Rav Huna, son of Rav Yehoshua, and said: Even if you say that the law with regard to a side post protruding four cubits into the alleyway applies in the case of an alleyway that is exactly eight cubits wide, in that it too does not require an additional side post. Whichever way you look at it, you are forced to arrive at this conclusion: If you say that the standing segment is greater, then the alleyway is permitted, because its standing segment is greater than the breached segment; and if you say that the breached segment is greater, then the protrusion is deemed a side post, as its width must be less than four cubits.

What might you say that would require an additional side post? Would you suggest that there is yet another possibility, that the two are exactly equal, the standing portion and the breach? This is an uncertainty with regard to rabbinic law, as carrying in an alleyway is forbidden only by rabbinic law, and the principle is that where there is an uncertainty with regard to a rabbinic law, one may assume the lenient position, as opposed to an uncertainty arising with respect to a Torah law, where one assumes the stringent position.

The Gemara considers a new case: Rav Ḥanin bar Rava said that Rav said: With regard to an alleyway that was breached,