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Biography

Simion was one of the top competitors in the Romanian national mathematical olympiads.¹ She graduated from the University of Bucharest in 1974, and immigrated to the United States in 1976.² She did her graduate studies at the University of Pennsylvania, earning a Ph.D. in 1981 under the supervision of Herbert Wilf.³⁴ After teaching at Southern Illinois University and Bryn Mawr College, she moved to George Washington University in 1987, and became Columbian School Professor in 1997.⁵

Recognition

She is included in a deck of playing cards featuring notable women mathematicians published by the Association of Women in Mathematics.⁶

Research contributions

Simion's thesis research concerned the concavity and unimodality of certain combinatorially defined sequences,⁷ and included what Richard P. Stanley calls "a very influential result" that the zeros of certain polynomials are all real.⁸

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 permutations and the permutations formed by interleaving two monotonic sequences are equinumerous, and found combinatorial enumerations of many permutation classes.⁹¹⁰ The "simsun permutations" were named after her and Sheila Sundaram, after their initial studies of these objects;¹¹¹² 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.¹³

Simion also did extensive research on noncrossing partitions, and became "perhaps the world's leading authority" on them.¹⁴

Other activities

Simion was the main organizer of an exhibit about mathematics, Beyond Numbers, at the Maryland Science Center, based in part on her earlier experience organizing a similar exhibit at George Washington University.¹⁵¹⁶ She was also a leader in George Washington University's annual Summer Program for Women in Mathematics.¹⁷ As well as being a mathematician, Simion was a poet and painter;¹⁸¹⁹ her poem "Immigrant Complex" was published in a collection of mathematical poetry in 1979.²⁰

Selected publications

• Simion, Rodica (1984), "A multi-indexed Sturm sequence of polynomials and unimodality of certain combinatorial sequences", Journal of Combinatorial Theory, Series A, 36 (1): 15–22, doi:10.1016/0097-3165(84)90075-X, MR 0728500.
• Simion, Rodica; Schmidt, Frank W. (1985), "Restricted permutations", European Journal of Combinatorics, 6 (4): 383–406, doi:10.1016/s0195-6698(85)80052-4, MR 0829358.
• Simion, Rodica; Ullman, Daniel (1991), "On the structure of the lattice of noncrossing partitions", Discrete Mathematics, 98 (3): 193–206, doi:10.1016/0012-365X(91)90376-D, MR 1144402.
• Simion, Rodica (2000), "Noncrossing partitions", Discrete Mathematics, 217 (1–3): 367–409, doi:10.1016/S0012-365X(99)00273-3, MR 1766277.

See also

• Cyclohedron

References

1. Crapanzano, Theresa (January 20, 2000), "GW mourns after math professor passes away", The GW Hatchet. https://www.gwhatchet.com/2000/01/20/gw-mourns-after-math-professor-passes-away/ ↩

2. Stanley, Richard P. (2000), "Rodica Simion: January 18, 1955 – January 7, 2000" (PDF), Pi Mu Epsilon Journal, 11: 83–86. /wiki/Richard_P._Stanley ↩

3. Stanley, Richard P. (2000), "Rodica Simion: January 18, 1955 – January 7, 2000" (PDF), Pi Mu Epsilon Journal, 11: 83–86. /wiki/Richard_P._Stanley ↩

4. Rodica Simion at the Mathematics Genealogy Project https://mathgenealogy.org/id.php?id=15214 ↩

5. Stanley, Richard P. (2000), "Rodica Simion: January 18, 1955 – January 7, 2000" (PDF), Pi Mu Epsilon Journal, 11: 83–86. /wiki/Richard_P._Stanley ↩

6. "Mathematicians of EvenQuads Deck 1", awm-math.org, retrieved 2022-06-18 https://awm-math.org/publications/playing-cards/deck1/#simion ↩

7. Wilf, Herbert (January 2000), Rodica Simion (1955–2000), Remarks at a special session of an AMS meeting in Washington, D.C.. /wiki/Herbert_Wilf ↩

8. Stanley, Richard P. (2000), "Rodica Simion: January 18, 1955 – January 7, 2000" (PDF), Pi Mu Epsilon Journal, 11: 83–86. /wiki/Richard_P._Stanley ↩

9. Stanley, Richard P. (2000), "Rodica Simion: January 18, 1955 – January 7, 2000" (PDF), Pi Mu Epsilon Journal, 11: 83–86. /wiki/Richard_P._Stanley ↩

10. Wilf, Herbert (January 2000), Rodica Simion (1955–2000), Remarks at a special session of an AMS meeting in Washington, D.C.. /wiki/Herbert_Wilf ↩

11. Zeilberger, Doron (January 2000), RODICA SIMION (1955-2000): An (almost) Perfect Enumerator and Human Being. /wiki/Doron_Zeilberger ↩

12. Sundaram, Sheila (2002), "Reminiscences of Rodica Simion", Advances in Applied Mathematics, 28 (3–4): 285–286, doi:10.1006/aama.2001.0785, MR 1899997. /wiki/Advances_in_Applied_Mathematics ↩

13. Deutsch, Emeric; Elizalde, Sergi (2012), "Restricted simsun permutations", Annals of Combinatorics, 16 (2): 253–269, arXiv:0912.1361, doi:10.1007/s00026-012-0129-6, MR 2927606, S2CID 115172092. /wiki/Annals_of_Combinatorics ↩

14. Stanley, Richard P. (2000), "Rodica Simion: January 18, 1955 – January 7, 2000" (PDF), Pi Mu Epsilon Journal, 11: 83–86. /wiki/Richard_P._Stanley ↩

15. Stanley, Richard P. (2000), "Rodica Simion: January 18, 1955 – January 7, 2000" (PDF), Pi Mu Epsilon Journal, 11: 83–86. /wiki/Richard_P._Stanley ↩

16. Bonin, Joseph E. (2002), "A remembrance of Rodica Simion", Advances in Applied Mathematics, 28 (3–4): 280–281, doi:10.1006/aama.2001.0783, MR 1899995. /wiki/Advances_in_Applied_Mathematics ↩

17. Stanley, Richard P. (2000), "Rodica Simion: January 18, 1955 – January 7, 2000" (PDF), Pi Mu Epsilon Journal, 11: 83–86. /wiki/Richard_P._Stanley ↩

18. Zeilberger, Doron (January 2000), RODICA SIMION (1955-2000): An (almost) Perfect Enumerator and Human Being. /wiki/Doron_Zeilberger ↩

19. Kalai, Gil (January 7, 2000), Rodica Simion: Immigrant Complex, Combinatorics and more. /wiki/Gil_Kalai ↩

20. Robson, Ernest M.; Wimp, Jet, eds. (1979), Against infinity: an anthology of contemporary mathematical poetry, Primary Press, pp. 65–66, ISBN 9780934982016. 9780934982016 ↩