Regina Tyshkevich
Regina Iosifovna Tyshkevich (; 20 October 1929 – 17 November 2019) was a Belarusian mathematician, an expert in graph theory, Doctor of Physical and Mathematical Sciences, professor of the Belarusian State University. Her main scientific interests included Intersection graphs, degree sequences, and the reconstruction conjecture. She was also known for an independent introduction and investigation of the class of split graphs and for her contributions to line graphs of hypergraphs. In 1998, she was awarded the Belarus State Prize for her book "Lectures in Graph Theory". Of note is her textbook "An Introduction into Mathematics", written together with her two  colleagues. In October 2009 an international conference "Discrete Mathematics, Algebra, and their Applications", sponsored by the Central European Initiative, was held in Minsk, Belarus in honor of her 80th anniversary. Regina Tyshkevich was a direct descendant of the Tyszkiewicz magnate family, therefore her colleagues sometimes called her "the countess of graph theory", which is a pun in the Russian language: the Russian word "граф" (graf) is a homonym for two words meaning "count" and "graph".