March 8, 2021

Purdue computer scientist wins George Pólya Prize in Applied Combinatorics

Note to journalists: A high-resolution photo of Alex Pothen is available via Google Drive. Journalists visiting campus should follow visitor health guidelines.

WEST LAFAYETTE, Ind. —The field of applied mathematics enables the ability to solve real-world problems through mathematical models and computational methods. The Society for Industrial and Applied Mathematics (SIAM) promotes research that will lead to new mathematical and computational techniques for solving challenging problems in science, engineering, industry and society.

SIAM has elected Purdue University computer scientist and applied mathematician Alex Pothen to receive its prestigious 2021 George Pólya Prize in Applied Combinatorics.

A professor of computer science, Pothen specializes in combinatorial scientific computing, graph algorithms, high-performance computing and bioinformatics. He was nominated for his research paper "What Color is Your Jacobian? Graph Coloring for Computing Derivatives,” which appeared in SIAM Review in 2005. He is being honored with his co-authors, Assefaw Gebremedhin of Washington State University and Fredrik Manne of the University of Bergen in Norway.

Graph coloring is a mathematical technique to divide a collection of objects into few groups so that a scarce resource can be used optimally. An example might be to group courses to be taught in a semester into time periods so that classrooms can be used effectively. Pothen’s article describes efficient algorithms to solve several variant coloring problems and then applies them to compute Jacobian and Hessian matrices — matrices of derivatives that are key calculus concepts. These enable scientists to solve nonlinear problems that could be modeled as optimization problems or differential equations, including machine learning.

His work provides a unifying framework for developing graph models and algorithms for 10 variant derivative matrix estimation problems. This work is being used in more than 50 areas of science and engineering, from robots that assist patients with impaired mobility to the dynamics of star formation.

Hungarian mathematician Pólya, who taught at Stanford University, was one of the leading mathematicians of the 20th century, and is well-known for his book “How to Solve It: A New Aspect of Mathematical Method.”  The George Pólya Prize was established in 1969 in his honor.  This honor is given out once every four years to individuals making significant contributions to applications of combinatorics, the branch of mathematics that explores finite, countable, discrete entities. It alternates every two years with the Pólya Prize in Mathematics. Earlier winners of the Pólya prize in combinatorics and mathematics include several celebrated mathematicians, including a Fields medalist (considered the Nobel prize of mathematics). The prize will be awarded during the 2021 SIAM annual meeting in July.

“I am very pleased that SIAM has recognized the significance of the research results of professor Pothen’s and his collaborators with this important award,” said Sunil Prabhakar, professor and head of Purdue’s Department of Computer Science. “It is also noteworthy that one of the co-recipients of the prize, Assefaw Gebremedhin, also has a Purdue connection — he was a research assistant professor at Purdue for several years.”

Gebremedhin was at Purdue from 2008-14.

Strengthening computer science is one of the Purdue Moves Initiatives intended to enhance the university’s strengths and prepare it for the future. Computer science drives today’s digital and connected society, but there is a dramatic shortfall in graduates with the skill sets necessary. The Purdue Moves Initiatives incorporates affordability and accessibility, online education, STEM leadership, world-changing research and transformative education measures to forge innovations and achievements that empower Purdue graduates to change the world for the better.

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Writer: Bella Vina

Media contact: Brittany Steff,  

Source: Alex Pothen,

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