John Paul Hempel ( Salt Lake City, Utah, October 14, 1935 ─ Rice Lake, Wisconsin, January 13, 2022) was an American mathematician specialising in

geometric topology In mathematics, geometric topology is the study of manifolds and maps between them, particularly embeddings of one manifold into another. History Geometric topology as an area distinct from algebraic topology may be said to have originated i ...

, in particular the topology of

3-manifold In mathematics, a 3-manifold is a space that locally looks like Euclidean 3-dimensional space. A 3-manifold can be thought of as a possible shape of the universe. Just as a sphere looks like a plane to a small enough observer, all 3-manifolds lo ...

s and associated algebraic problems, mainly in group theory.

Early life and career

Hempel was born in Salt Lake City, Utah. In 1957 he graduated from the University of Utah with a degree in mathematics. In 1962, he defended his thesis at the University of Wisconsin-Madison, under the supervision of

R. H. Bing R. H. Bing (October 20, 1914 – April 28, 1986) was an American mathematician who worked mainly in the areas of geometric topology and continuum theory. His father was named Rupert Henry, but Bing's mother thought that "Rupert Henry" was too ...

. He was a professor at Rice University until the time of his death. He was married to Edith, whom he married on September 1, 1965, in

Houston, Texas Houston (; ) is the most populous city in Texas, the most populous city in the Southern United States, the fourth-most populous city in the United States, and the sixth-most populous city in North America, with a population of 2,304,580 in ...

. He had 1 son and 3 grandchildren. Outside of mathematics, Hempel was a nature enthusiast. As a child he was

adventurous An adventure is an exciting experience or undertaking that is typically bold, sometimes risky. Adventures may be activities with danger such as traveling, exploring, skydiving, mountain climbing, scuba diving, river rafting, or other extreme spo ...

, and taught himself to

mountain bike A mountain bike (MTB) or mountain bicycle is a bicycle designed for off-road cycling. Mountain bikes share some similarities with other bicycles, but incorporate features designed to enhance durability and performance in rough terrain, which ...

. He was also fascinated by camping, climbing, skiing and

boating Boating is the leisurely activity of travelling by boat, or the recreational use of a boat whether Motorboat, powerboats, Sailing, sailboats, or man-powered vessels (such as rowing and paddle boats), focused on the travel itself, as well as sp ...

. In addition, he knew how to play the piano. In 2013, Hempel was elected a fellow of the American Mathematical Society. Hempel showed that the fundamental groups of 2 manifolds are residually finite. He also introduced the study of the

curve complex In mathematics, the curve complex is a simplicial complex ''C''(''S'') associated to a finite-type surface ''S'', which encodes the combinatorics of simple closed curves on ''S''. The curve complex turned out to be a fundamental tool in the stu ...

into 3-manifold topology. Hempel wrote a book called

3-manifolds In mathematics, a 3-manifold is a space that locally looks like Euclidean 3-dimensional space. A 3-manifold can be thought of as a possible shape of the universe. Just as a sphere looks like a plane to a small enough observer, all 3-manifolds loo ...

in 1976. His research was in topology.

References

{{DEFAULTSORT:Hempel, John 1935 births 2022 deaths 20th-century American mathematicians Topologists Rice University faculty University of Utah alumni Mathematicians from Utah