Rodica Eugenia Simion (January 18, 1955 – January 7, 2000) was a

Romanian-American Romanian Americans are Americans who have Romanian ancestry. According to the 2017 American Community Survey, 478,278 Americans indicated Romanian as their first or second ancestry, however other sources provide higher estimates, which are most ...

mathematician. She was the Columbian School Professor of Mathematics at George Washington University. Her research concerned

combinatorics Combinatorics is an area of mathematics primarily concerned with counting, both as a means and an end in obtaining results, and certain properties of finite structures. It is closely related to many other areas of mathematics and has many appl ...

: she was a pioneer in the study of permutation patterns, and an expert on noncrossing partitions.

Biography

Simion was one of the top competitors in the Romanian national

mathematical olympiads Mathematics competitions or mathematical olympiads are competitive events where participants complete a math test. These tests may require multiple choice or numeric answers, or a detailed written solution or proof. International mathematics comp ...

. She graduated from the University of Bucharest in 1974, and immigrated to the United States in 1976.. She did her graduate studies at the University of Pennsylvania, earning a Ph.D. in 1981 under the supervision of Herbert Wilf. After teaching at Southern Illinois University and Bryn Mawr College, she moved to George Washington University in 1987, and became Columbian School Professor in 1997.

Recognition

She is included in a deck of playing cards featuring notable women mathematicians published by the Association of Women in Mathematics.

Research contributions

Simion's thesis research concerned the

concavity In calculus, the second derivative, or the second order derivative, of a function is the derivative of the derivative of . Roughly speaking, the second derivative measures how the rate of change of a quantity is itself changing; for example, ...

and unimodality of certain combinatorially defined sequences,. and included what Richard P. Stanley calls "a very influential result" that the zeros of certain polynomials are all real. Next, with Frank Schmidt, she was one of the first to study the combinatorics of sets of permutations defined by forbidden patterns; she found a bijective proof that the

stack-sortable permutation In mathematics and computer science, a stack-sortable permutation (also called a tree permutation) is a permutation whose elements may be sorted by an algorithm whose internal storage is limited to a single stack data structure. The stack-sortab ...

s and the permutations formed by interleaving two monotonic sequences are equinumerous, and found combinatorial enumerations of many permutation classes. The "simsun permutations" were named after her and Sheila Sundaram, after their initial studies of these objects; a simsun permutation is a permutation in which, for all ''k'', the subsequence of the smallest ''k'' elements has no three consecutive elements in decreasing order. Simion also did extensive research on noncrossing partitions, and became "perhaps the world's leading authority" on them.

Other activities

Simion was the main organizer of an exhibit about mathematics, ''Beyond Numbers'', at the

Maryland Science Center The Maryland Science Center, located in Baltimore's Inner Harbor, opened to the public in 1976. It includes three levels of exhibits, a planetarium, and an observatory. It was one of the original structures that drove the revitalization of the B ...

, based in part on her earlier experience organizing a similar exhibit at George Washington University. She was also a leader in George Washington University's annual Summer Program for Women in Mathematics. As well as being a mathematician, Simion was a poet and painter;. her poem "Immigrant Complex" was published in a collection of mathematical poetry in 1979..

Selected publications

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References