Eli, Baruch she'Kivanta! The Acharonim discuss this question.

1) The Gemara (3b, two-thirds of the way down the page) states that when the Beraisa (beginning of 3b) tells us that the house of less than 4 X 4 Amos cannot be used as a connection between two cities, this means that it is even less important than "Burganin" -- the straw huts which bird hunters use. The Gemara explains that the reason is that Burganin are "Chazu l'Miltaihu" -- they can be used for their specific purpose, namely for the hunters to sleep there overnight -- while a house of less than 4 X 4 cannot be used for anything.

2) Based on this Gemara, the Aruch la'Ner raises the question of a kosher Sukah during Sukos which is smaller than 4 X 4. This is Chazi l'Miltei on Sukos, namely one can sit inside it and fulfill the mitzvah of Sukah, so perhaps one can say that it is similar to Burganin and may be used as a connection between the two cities. On the other hand, one might argue that it is not equivalent to Burganin because the latter are Chazu l'Miltaihu all year round, while the Rosho v'Rubo Sukah cannot be used as a connection between the two cities all year round because it is less than 4 X 4 and, therefore, this may mean that even on Shabbos during Sukos it cannot make the connection.

3) It seems that the Aruch la'Ner understood that it is obvious that the minimum size of Burganin that the Gemara discusses is 4 X 4. However, the Ritva writes that the Gemara means that even if the Burganin are less than 4 X 4, they can still be used to connect the cities. This is because the Ritva learns that Chazu l'Miltaihu for Burganin means that that they are wayside booths used to provide water and food for travelers, and for this it is sufficient to have a booth less than 4 X 4.

4) The Sefas Emes writes that according to the Ritva, a Rosho v'Rubo Sukah connects between the two cities on Shabbos on Sukos, because, according to the Ritva, a Sukah does not require 4 X 4. In addition, the Sefas Emes cites the Gemara below (7a) that since one Tefach is sufficient to be called a third wall for a Sukah, it is also sufficient to be called a third wall to carry inside its area on Shabbos during Sukos. One learns from 7a that if something is considered a dwelling place as far as Sukos is concerned, it is also considered a dwelling place as far as the Halachos of Shabbos on the Shabbos during Sukos is concerned. Therefore, the Sefas Emes concludes that the Rosho v'Rubo Sukah can make a connection between two cities on Sukos.

Gmar Chasimah Tovah,

Dovid Bloom

Here are some further thoughts on the Sefas Emes I cited above:

1) There seems to be a question on the Sefas Emes from the Gemara at the beginning of 3b. After the Gemara finishes citing the Beraisa (which starts on 3a) about the house which is less than 4 X 4, the Gemara suggests that this Beraisa follows the opinion of Rebbi that a Sukah must be a minimum of 4 X 4, which is why a house of less than 4 X 4 is also not considered as a house for other Halachos. The Gemara then refutes this suggestion and states that the Beraisa could also follow the Rabanan who hold that a Sukah of less than 4 X 4 is also valid. The distinction is that the Rabanan said that less than 4 X 4 is sufficient only for a Sukah because it is enough that a Sukah is a temporary dwelling. In contrast, the Dinim mentioned in the Beraisa refer to things for which one requires a permanent house, and therefore a minimum of 4 x 4 is obligatory.

2) One sees from this Gemara that to make a connection between two cities for Shabbos purposes, a permanent house is needed. Now I suggest that there is no contradiction from this to what we saw above in the name of the Ritva that Burganin can be less than 4 x 4. This is because the Gemara says that Burganin are Chazi l'Miltaihu -- they do their job even if they are less than 4 x 4. This means that the bird hunter finds the Burganin quite sufficient for his purposes because he can sleep there overnight, which is all he needs. In fact, the bird hunter can sleep overnight there for the entire summer whenever he is in the field. So the Burganin can be considered a permanent house for the purpose it serves. In contrast, the Rosho v'Rubo Sukah is not permanent. The only reason why a person who is at home would live in such a Sukah is because of the Mitzvah of Sukah, and this last only seven days. Therefore, a Rosho v'Rubo Sukah is a temporary dwelling, and my argument is that it would not be considered sufficient to make the connection between two cities, according to the criterion stated on 3b that the examples mentioned in the Beraisa are of things for which one requires a permanent house.

3) I will mention another question on the Sefas Emes, which is really very similar in principle to the question I have just asked, but it may just make things a bit more vivid. This is the question of a Mezuzah in a Sukah. The Gemara (Yoma 10b) states that according to the Rabanan, whom the Halachah follows, a Sukah is exempt from a Mezuzah because it is a temporary dwelling. This is recorded as the Halachah in Shulchan Aruch (Yoreh De'ah 286:11). However, do Burganin of less than 4 x 4 need a Mezuzah according to the Ritva? The Rashash on 3b brings a proof from the Gemara of Chazi l'Miltaihu that an entrance which leads into a house requires a Mezuzah even though it is less than 4 x 4. This is because the entrance is Chazi l'Miltaihu. It does the job of being an entrance even though it is less than 4 x 4. The Rashash brings support from this Gemara for the very important and relevant Halachah -- that if a house possesses small rooms inside larger rooms, the small rooms require Mezuzos even thiough they are less than 4 x 4 Amos, because they fulfil their purpose of storing items there, even though they are small.

4) At any rate, we see that Burganin require a Mezuzah even though they are under 4 x 4. This proves that Burganin are more permanent than a Rosho v'Rubo Sukah. The reason is that the bird hunter can use them all summer long to sleep in, while the small Sukah is used only for one week in the year. Therefore, there would be no proof from the Burganin smaller than 4 x 4 of the Ritva that a Rosho v'Rubo Sukah can also connect between the two cities.

Kol Tuv,

Dovid Bloom

Here are additional thoughts on the Chidush of the Sefas Emes:

1) The Sefas Emes, in his second argument, cites support for his Chidush from the Gemara below (7a) that we say a Migo. However, if one looks carefully at the words of the Sefas Emes, one notices that he himself hints that the Migo that he is saying is slightly different from the Migo that the Gemara says. The Migo that the Gemara gives is about a wall. We say that since ("Migo") the third wall of one Tefach is a wall for the Sukah, it is also called a wall for Shabbos purposes during Sukos. The Sefas Emes takes this Migo further. He writes that on Sukos we say that since ("Migo") the Sukah is considered a dwelling place for Sukos purposes, it is also considered a Dirah for all purposes. We see that the Sefas Emes has extended the Migo of the Gemara from a Migo to make one wall into a Migo to make an entire dwelling place. Now we may ask on the Sefas Emes, in the same way that I asked in my previous reply: How can he say that the Rosho v'Rubo Sukah becomes a dwelling place for all purposes on Sukos, since we know that such a Sukah does not require a Mezuzah even during the seven days of Sukos, and if so why should we say it is considered a valid Burganin on Shabbos during Sukos?

2) In addition, there is another question that can be asked on the Sefas Emes from the Gemara in Eruvin 21a which states that there is no such Halachah as Burganin in Bavel. This is because flooding is frequent there. Rashi (DH Ein) explains that the flood might wash away the Burganin and therefore they are worthless. Now it would certainly seem that even in Bavel the floods do not come every week. A Burganin could presumably often survive even in Bavel for a few weeks. Nevertheless, we see from the Gemara there that since the Burganin are not capable of lasting a significant amount of time, they do not possess the necessary permanence to be considered a dwelling place fit to lengthen the boundary of the city. We learn from there that it is not sufficient for the Burganin to be useful merely for one week. Therefore, we have a question on the Sefas Emes from Eruvin 21a.

3) In fact, this explanation of the Sefas Emes became part of a recent Halachic controversy here in Yerushalayim. As is well known, for many years the Poskim in Yerushalayim have been occupied with the question on what days should Megilas Esther be read on Purim in the various suburbs. Where I live, in Ramot, there is still a dispute on this point. One of the questions involved is whether Ramot is considered to be inside the Halachic boundary of Yerushalayim. In recent years, those who advocate reading in Ramot on 15 Adar (like the rest of Yerushalayim) have suggested that Burganin be erected on the Ramot road, between the main part of Yerushalayim and Ramot, and this would help to extend the boundary. However, there are practical difficulties involved in leaving the huts on the side of the road for too long. The advocates of the Burganin cited the Sefas Emes as a source that one does not require Burganin that are there for a long time, since the one-week- long Sukah is also sufficient. However, other leading Talmidei Chachamim argued that it is difficult to rely on the Sefas Emes in the light of the questions which can be asked upon him, as we have seen.

Kol Tuv,

Dovid Bloom