Yosef Rosin

Joseph Rosen
Born	1858 Rogachev
Died	1936 Vienna

Joseph Rosen (Yiddish: יוסף ראָזין, Yosef Rosin), known as the Rogatchover Gaon, ("Genius of Rogachev"), and also often referred to by the title of his main work Tzofnath Paneach ("Decipherer of Secrets"), (Rogachev, 1858 – Vienna, 5 March 1936), was a rabbi and one of the most prominent talmudic scholars of the early 20th-century, known as a genius (gaon) because of his photographic memory and ability to connect sources from the Talmud to seemingly unrelated situations. He has been described as the foremost Talmudic genius of his time.

He was born in Rogachev, now Belarus, into a Hasidic family of Chabad hasidim, and was educated in the local cheder (Torah school for small children). His unusual capabilities were noticed at the age of thirteen, when he was sent to study in Slutzk along with Rabbi Chaim Soloveitchik, five years his senior, under the Beis Halevi, Rabbi Yosef Dov Soloveitchik. He subsequently studied under Rabbi Yehoshua Yehuda Leib Diskin (Maharil Diskin) in Shklov. He then assumed (in 1889) the rabbinate of the Hasidic community in Dvinsk for almost 50 years, where his non-Hasidic counterpart was Rabbi Meir Simcha of Dvinsk; they served in parallel until the late 1920s, and enjoyed excellent relations.

Among those who received semicha (Rabbinic ordination) from him were the seventh Lubavitcher Rebbe, Rabbi Menachem Mendel Schneerson; Rabbi Mordecai Savitsky (1911-1991) of Boston; Rabbi Zvi Olshwang (1873–1959?) of Chicago, who was a brother-in-law of Rabbi Shimon Shkop; and Rabbi Avraham Eliyahu Plotkin (1888-1948), the author of Birurei Halachot (a copy of the actual semicha is included in that work).

...
Wikipedia