In the Ba’i Rav they said that Rav permits a Bi’as Mitzvah on Shabbos and Shmuel prohibits it and in Naharda’e they say the opposite. (1)
It is forbidden to squeeze a sponge on Yom Tov. (2)
Although Rebbi Shimon holds that an unintended Melachah is permitted, if it is a Pe’sik Re'isha (the Melachah is inevitable) it is forbidden.
Rav follows the opinion of Rebbi Yehudah that an unintended Melachah is forbidden and Shmuel follows the opinion of Rebbi Shimon that it is permitted. (3)
Bais Shamai holds a Ketanah who is younger than the age of seeing blood; any blood that she sees the first four nights of marriage is regarded as the blood of Besulim.
Bais Hilel holds that any blood the newly married Ketanah sees is regarded as the blood of Besulim until the wound heals. (4)
Bais Shamai holds that if a girl is old enough to see blood but she has not yet seen blood, any blood that she sees the first night is regarded as the blood of Besulim. (5)
Shmuel says that it is permitted to enter a tight passageway on Shabbos even though pebbles are dislodged.
A Chasan is Patur from Krias Shema for four nights if he has not yet done a Bi’as Mitzvah. (6)
A mourner is Chayav in all of the Mitzvos with he exception of Tefilin.
Rebbi Shimon permits having relations on Shabbos because most people know how to have Bi’ah without drawing blood.
If someone opens up a sore on Shabbos for the purpose of making an opening he is Chayav. (6)
A BIT MORE
1. Ba’i Rav was the place of Rav and Naharda’e was the place of Shmuel, each place was lenient for themselves.
2. Because it is inevitable that some of the absorbed liquid will be squeezed out.
3. Even though Rav follows the opinion of Rebbi Yehudah he still may hold that a Bi’as Mitzvah on Shabbos is permitted because it is a destructive act which is permitted on Shabbos.
4. As long as she continues to see blood when having relations the wound has not yet healed.
5. Bais Hilel holds that any blood that she sees the first four nights until Motzae’i Shabbos is regarded as the blood of Besulim
6. One Tana in the Beraysah holds that the Chasan is Chayav in Krias Shema Friday night.
7. If it is for the purpose of extracting fluid it is permitted.