Riho Terras (mathematician)

Riho Terras (June 13, 1939 – November 28, 2005)^[1] was an Estonian-American mathematician.^[2] He was born in Tartu, Estonia, and moved to Ulm, Germany, before starting school.^[3] In 1951, he emigrated to the United States along with his mother.^[2][3] In 1965, he was given the Milton Abramowitz award for his studies at the University of Maryland.^[4] He finished his PhD in 1970 at the University of Illinois Urbana-Champaign.^[5]

He is known for the Terras theorem about the Collatz conjecture, published in 1976,^[6] which proved that the conjecture holds for "almost all" numbers and established bounds for the conjecture.^[7][8]

He married fellow mathematician Audrey Terras.^[9]