(Mishnah): To make Eruv Techumim for many people, one designates a barrel [of food or drink] and says 'This is for everyone in the city who wants to go to the mourner's house or the hall of the [wedding] feast';

Anyone who accepted [to rely on the Eruv] before Shabbos may rely on it. One who accepted after dark may not, for one may not be Me'arev after dark.

(Gemara) Question: [Our Mishnah does not teach that] he is Mezakeh for them. Why does it not teach that he is Mezakeh for them [like it taught above about Eruvei Chatzeros]?

Answer #1 (Shmuel): There (Eruvei Chatzeros) it teaches that he is Mezakeh for them - he must be Mezakeh for them (to acquire Reshus). Here (Eruvei Techumim) that it did not teach that he is Mezakeh for them, he need not be Mezakeh.

Answer #2 (R. Yochanan): Kal v'Chomer [also here he must be Mezakeh for them]! There, Eruvei Chatzeros is mid'Rabanan, you say that we are (must be) Mezakeh. Eruvei Techumim mid'Oraisa, all the more so!

Rav holds like R. Yochanan.

(R. Yosi bei R. Bun): [Shmuel holds that Eruvei Chatzeros require Zechiyah] in order to make all of the Reshuyos like one. (This does not apply to Eruvei Techumim.)