(Mishnah): If it is full of dirt... [they may be Me'arev together but not separately].

Question: Stam (without specifying, we do not assume that) dirt is Batel (will be left there permanently)!

(Mishnah in Ohalos): If [Tum'as Mes was in a house, and] it was full of straw or pebbles (these are like dirt regarding Bitul) and one was Mevatel them (decided to leave them there permanently), they are Batel. (When gauging whether or not there is a gap of a cubic Tefach above the Tum'ah for Tum'as Ohel, we do not include their space);

Inference: They are Batel only because he explicitly was Mevatel them!

Answer #1 (Rav Huna): A Stam Mishnah in Ohalos is assumed to be R. Yosi. (He argues with our Tana).

Rejection: R. Yosi holds that dirt and pebbles are Batel without specifying!

(Beraisa - R. Yosi): If straw [in a house] will not be removed (we know that it is not needed, but he did not explicitly Mevatel it), it is like Stam dirt (about which we have no knowledge), it is Batel;

If dirt will be removed [we know that it is needed], it is like Stam straw, it is not Batel.

Answer #2 (Rav Asi): A Stam Mishnah in Eruvin is assumed to be R. Yosi. (He argues with the Mishnah in Ohalos.)

Answer #3 (Rav Huna brei d'Rav Yehoshua): You cannot ask from Tum'ah to Shabbos!

Bitul for Tum'ah must be permanent. Regarding Shabbos, even a wallet is Batel (for one may not move it on Shabbos)!

Answer #4 (Rav Ashi): You cannot ask from [Bitul in] a house to a ditch!

People normally [permanently] fill in a ditch. They do not normally fill up a house!

(Mishnah): If one put a plank four wide [across the ditch...]

(Rava): The plank must be four wide only if the length of the plank goes along the width of the ditch. If it goes along the length (part rests on the ground, and part is supported on pegs over the ditch), if it is any width it can be Mema'et [the width of the ditch from four. Since one can step on the plank, it is now easy to step to the other Chatzer, for less than four Tefachim remain].

(Mishnah): The same applies to two balconies opposite each other.

(Rava): A plank four wide joins them only if they are opposite each other. If not, or if one of them is higher than the other, it does not join them (Rashi. Tosfos - they are like one when they are less than four apart only if they are opposite each other. If not, or if one of them is higher than the other, they may not be Me'arev together, for it is hard to walk from one to the other);

This is only if they are three Tefachim apart. If not, they are like one.

(Mishnah): If a haystack [along the entire border] between two Chatzeros is 10 tall, they may be Me'arev separately, but not together;

Members of both Chatzeros may feed their animals from the stack.

If the stack became less than 10 Tefachim [tall along the entire border, or for more than 10 Amos], they may be Me'arev together, but not separately.

(Gemara - Rav Huna): One may feed his animal from the stack, but he may not put into his Kli and feed it. (The hay is Muktzeh for the Mechitzah. Alternatively, we are concerned lest he inadvertently diminish the wall, which would invalidate the Eruvin, and people will still carry.)

Inference: He may bring his animal there to eat. (We are not concerned lest he put into his Kli.)

Question (Rav Huna citing R. Chanina): On Shabbos, one may bring his animal to eat from attached grass (we are not concerned lest he detach, for this is forbidden mid'Oraisa), but not from Muktzeh [lest he take some to feed it. This is forbidden only mid'Rabanan, so people are not so careful about it. Also regarding the haystack, we should be concerned lest he transgress a mid'Rabanan law!]

Answer: (Indeed, he may not bring his animal there.) He may only stand in front of it [giving it no other place to go], and it goes by itself.

(Rav Huna): He may not put into his Kli and feed it.

Question (Beraisa): If a house between two Chatzeros (a house from each Chatzer opens to it) was filled with straw, the Chatzeros may be Me'arev separately but not together;

Members of both Chatzeros may put straw into their Kelim and feed their animals.

If the straw became less than 10 Tefachim, both are forbidden [to carry in the Chatzeros].

To permit [the other Chatzer], one locks [the door of] his house [that opens to the middle house] and is Mevatel his Reshus [to the other Chatzer]. He is forbidden, and the other [Chatzer] is permitted.

The same applies to a pile of straw, if different parts of it are in the Techumim of different cities.

Summation of question: They put straw into their Kelim and feed their animals!

Answer: Since a house has a ceiling, people will notice if the straw gets too low. They will not notice if a stack outdoors gets below 10. (Even though one may not take the straw because it is Muktzeh, this only applies below 10. Above 10 is not needed for the Mechitzah.)

(Beraisa): If the straw became less than 10 Tefachim, both are forbidden.

Inference: When the straw is at least 10, they are permitted.

Question: This implies that a Mechitzah [in a house] is valid even if it does not reach to the ceiling! (This is unlike the Halachah (72b).)

Answer #1 (Abaye): The case is, the ceiling is less than 13 tall, and the stack is 10. (It 'reaches' the ceiling, through Lavud);

Answer #2 (Rav Huna brei d'Rav Yehoshua): We can even say that the ceiling is 10 and the stack is slightly more than seven. Any gap less than three is Lavud.

Question: According to Abaye, we understand why the Beraisa says that the straw must be 10. How does Rav Huna explain this?

Answer: It means that the straw must be considered like 10 (in reality, or through Lavud).

(Beraisa): Both are forbidden.

Inference: If new residents come on Shabbos (like the people of the other Chatzer, who had no connection to this Chatzer until the straw was diminished), they forbid!

Rejection: Perhaps the Beraisa forbids only when it became diminished before Shabbos.

(Beraisa): To permit, one may lock his house and be Mevatel his Reshus.

Question: Why must he do both of these?

Answer #1: Indeed, it suffices to lock or be Mevatel.

Answer #2: [Even though one suffices to permit the others,] since he is used to carrying, both of these are required [lest he take things out. Rashi - the Tana always requires one who is Mevatel to also lock his house. Tosfos - he requires this only the first time. Afterwards, he is used to not carrying. Me'iri - the Beraisa teaches that even if he is Mevatel, he must lock it.]

(Beraisa): He is forbidden, and the other is permitted.

Objection: This is obvious! (The Mevatel is always forbidden.)

Answer: The case is, the one permitted was later Mevatel his Reshus back to the other. The Tana teaches that Bitul after Bitul does not work.

(Beraisa): The same applies to a pile of straw, if different parts of it are in the Techumim of different cities. (People of each city may take from their side. We are not concerned lest they take from the other side.)

Objection: This is obvious!

Answer: This is a Chidush according to R. Akiva, who says that Techumim are forbidden mid'Oraisa;

One might have thought that we decree to forbid [feeding animals], lest one take from the other Techum. The Beraisa teaches that this is not so.

(Mishnah): One may make Shituf in a Mavoy [on behalf of everyone] by taking a barrel (e.g. of wine) and saying that it is for everyone in the Mavoy. He may ask [even] any of the following to be Mezakeh (acquire) on behalf of them - his mature son or daughter, his Yisrael male or female slave, or his wife;

He cannot be Mezakeh through his small son or daughter, or his Kena'ani male or female slave, because they can acquire only for him.

(Gemara - Rav Yehudah): One must lift the barrel for Shituf a Tefach off the ground.

(Rava): The elders of Pumbedisa (Rav Yehudah and his academy) taught this and another teaching.

(The other teaching): One who makes Kidush must drink [at least] Malei Lugmav (the amount that one can hold in his mouth when one cheek sticks out). If he did not, he did not fulfil his obligation.

(R. Chaviva): They taught also the following:

(Rav Yehudah): We may make a bonfire for a Yoledes on Shabbos.

Assumption: This is permitted for a Yoledes, but not for other sick people. It is permitted only in winter, but not in summer.

Rejection: R. Chiya bar Avin taught that if someone let blood and got chilled, we may make a bonfire for him, even in summer.

(Ameimar): They taught also the following:

Question: What tree is [assumed to be] an Asheirah, even though we do not see that it is worshipped?

Answer #1 (Rav): If the priests [of idolatry] guard it and do not eat its fruits, it is an Asheirah.

Answer #2 (Shmuel): [Even] if they say 'the dates are for Bei Nitzrefei (an idolatry)', the tree is forbidden, for they make beer from the dates and drink it on their festival.

(The elders of Pumbedisa): The Halachah follows Shmuel.