Famous for his work in the mathematical sub-fields of low-dimensional topology and geometric group theory, this University of California-Berkeley professor proved the Poincaré Conjecture and devised the Stallings Theorem about Ends of Groups.
After earning his undergraduate degree from the University of Arkansas, he received his mathematics doctorate from Princeton University.
He was the 1970 recipient of the American Mathematical Society's Frank Nelson Cole Prize in Algebra.
He was born and raised in Morrilton, Arkansas, and he later lived and worked in Berkeley, California.
He and fellow American mathematician David Gale were contemporaries.