What is Marina Ratner?
[[File:Marina Ratner.jpeg|thumb|Marina Ratner in 1988]] '''Marina Evseevna Ratner''' ({{lang-ru|Мари́на Евсе́евна Ра́тнер}}; October 30, 1938 – July 7, 2017) was a Russian-American professor of mathematics at the [[University of California, Berkeley]]. She worked in ergodic theory. She was born in [[Moscow]], and of [[Jewish]] descent.<ref>{{Cite web|url=https://www.agnesscott.edu/lriddle/women/ratner.htm|title=Biography of Marina Ratner|last=Larry Riddle|website=agnesscott.edu}}</ref> Around 1990, she proved a group of major theorems concerning unipotent flows on homogeneous spaces, known as Ratner's theorems.<ref>{{Cite book|title=Ratner's theorems on unipotent flows|last=Morris, Dave Witte|date=2005|publisher=University of Chicago Press|isbn=0-226-53983-0|location=Chicago|citeseerx=10.1.1.240.444|oclc=57965722}}</ref> Ratner was elected to the American Academy of Arts and Sciences in 1992,<ref>{{Cite web|url=https://www.amacad.org/multimedia/pdfs/classlist.pdf|title=Membership list|website=American Academy of Arts and Sciences|language=en}}</ref> awarded the Ostrowski Prize in 1993 and elected to the [[United States National Academy of Sciences|National Academy of Sciences]] the same year. In 1994, she was awarded the John J. Carty Award from the National Academy of Sciences.<ref name=Carty>{{cite web|title=John J. Carty Award for the Advancement of Science |url=http://www.nasonline.org/site/PageServer?pagename=AWARDS_carty |publisher=National Academy of Sciences |access-date=25 February 2011 |url-status=dead |archive-url=https://web.archive.org/web/20101229180532/http://www.nasonline.org/site/PageServer?pagename=AWARDS_carty |archive-date=29 December 2010 }}</ref> Ratner died in [[Berkeley, California]] on July 7, 2017 of a [[stroke]] at the age of 78.<ref>{{Cite web|url=https://math.berkeley.edu/about/history/in-memoriam|title=In Memoriam|website=Department of Mathematics at University of California Berkeley|access-date=2017-07-16|archive-date=2017-04-01|archive-url=https://web.archive.org/web/20170401145