Roger Charles Alperin (January 8, 1947 – November 21, 2019) was an American mathematician, best known for his work in group theory, including its connections with geometry and topology. He was a professor at the University of Oklahoma and at San Jose State University.

Alperin was born on January 8, 1947, in Cambridge, Massachusetts.^[1] He received a bachelor's degree from the University of Chicago,^[2] and his PhD from Rice University in 1973. His thesis was supervised by Stephen M. Gersten, and was titled Whitehead Torsion of Finite Abelian Groups.^[3] After temporary positions at Brown University, Haverford College, and Washington University in St. Louis, Alperin took a permanent position at the University of Oklahoma in 1978.^[4] He was eventually promoted to full professor at the University of Oklahoma, but resigned his position to move to California in 1987.^[4] Upon moving to California, he found a position at San Jose State University, which he held until his retirement in 2015.^[4]

Alperin died on November 21, 2019, at his home in Carlsbad, California.^[4]

Alperin's work on real trees in the 80s (partly joint with Hyman Bass and Kenneth Moss) helped to stimulate interest in these objects, and helped establish them as a basic tool in geometric group theory.^[4] Alperin has also done foundational work on the mathematical theory of origami.^[1]

• Roger C. Alperin publications indexed by Google Scholar