(Mishnah): There are two [primary] oaths [of Bituy, that one will or will not do something], which are four [in all];

There are two [primary] Yedi'os (awarenesses) of Tum'ah, which are four [in all];

There are two kinds of Yetzi'ah (taking things to a different Reshus) on Shabbos, which are four;

There are two appearances of Tzara'as, which are four.

(Gemara) Question: [The first Mishnah in Shabbos says that there are two Yetzi'os that are four inside, and two that are four outside. Our Mishnah says "two that are four." Does it mean] two for Chiyuv [full Hotza'ah, i.e. Akirah and Hanachah, and full Hachnasah], and two for Petur (Akirah alone or Hanachah alone, whether for Hotza'ah or Hachnasah)?

Or, [does it mean like the Mishnah in Shabbos, that there are two that are] four for Chiyuv [the Ba'al ha'Bayis did Hotza'ah or Hachnasah, and likewise for the Oni], and four for Petur (the Ba'al ha'Bayis did Akirah alone or Hanachah alone, and likewise for the Oni)?

Answer #1: We learn from this (our Mishnah). There are two Shevuos, which are four. (Surely there are not eight! Rather, the first Perush is correct.)

Rebuttal (R. Ba): There (Shevuos), all of them are liable. However, here (Shabbos) it comes to teach Chiyuv and Petur. (We cannot resolve the question.)

Answer #2 (R. Yosi): We learn from our Mishnah. There are two Shevuos which are four. [All] are for Chiyuv. Similarly, Yetzi'os ha'Shabbos are two that are four, all are liable! This teaches [like the latter Perush,] four Chiyuvim and four exemptions.