I have a difficulty. How can we say on Shavuot that it is "the day of the giving of our Torah"?! Do we not conclude like R. Yose (Shabbat 86b) that the Torah was given on the 7th of Sivan? After all, we do conclude that separation from sexual intercourse [of man and wife, in regard to certain laws of Tumah] requires six half-days, as is written in Yore Deah 196. [R. Yose's opinion -- that the Torah was given on the 7th of Sivan -- is based on a need for husband and wife to separate a full three days. Since the Halakha today requires a 3 days for this particular separation, presumably R. Yose is correct about the date of Revelation.] (And I believe I've seen this question before in some Poseik's writings.) But in our calendar, Shavuot is always on the 6th of Sivan!