Where can I find the commentaries of the Rif and of the Rosh on Tractates Nazir and Sotah? They're not in my gemara (Oz v'Hadar), and I was wondering if they were appended to a different tractate?
To my surprise, it turns out that neither the Rif nor the Rosh ever penned commentaries to those two masekhtas. According to the Jewish Encyclopedia articles ("Alfasi, Isaac ben Jacob" and "Asher ben Jehiel", respectively), the Rif's Sefer haHalakhot covers only Berakhot, Shabbat, Eruvin, Pesachim, Ta'anit, Beitzah, Rosh haShana, Yoma, Sukkah, Megillah, Mo'ed Qatan, Yevamot, Ketubot, Gittin, Qiddushin, Nedarim, Chullin, Bava Qamma, Bava Metzia, Bava Batra, Sanhedrin, Makkot, Shevu'ot and Avodah Zarah (link).
The commentary of the Rosh covers only Seder Zeraim (except for Berakhot), tractates Nedarim and Tamid, and all of Seder Taharot. The digest of those commentaries that was composed by his son, titled "Pisqei haRosh", is appended to a range of other tractates as well (just taking a few randomly from the shelf, I found it on Bava Qama, Sanhedrin and Menachot), though is evidently not appended to all of them. The Jewish Encyclopedia article doesn't list which tractates it is found on and which it is not, though it appears then to be totally absent from Nazir and Sotah amongst others (link). How many others, I don't know.
As Shimon bM's already answered:
According to Wikipedia, there is an opinion that the halachic compendium of the Rosh (his best known work) is a commentary on the Rif, rather than a commentary directly on the talmud. As such it seems to me that wouldn't exist on any masechta that the Rif didn't write about (Wikipedia cites the Shach, as quoted in Kelalei HaRif, Rabbeinu Asher VeTur printed before the Rosh on Shabbat, Klal 2). The existance of the Rosh on any masechta that the Rif didn't write about would disprove this opinion of the Shach. (There is a differing opinion that the Rosh wrote on the Talmud directly - Wikipedia cites the S'dei Chemed klallei haposkim s.v. Rosh.)
Since the Piskei HaRosh (compiled by his son) is a summary of the halachic conclusions in the aforementioned compendium, it wouldn't exist on any masechta where the Rosh didn't write (and by implication, any masechta where the Rif didn't write).