The Four-Color Theorem Project

Students work on arranging and describing Kenneth Appel’s Papers.

From October to November 2017, the Illinois Geometry Lab’s program devoted to showcasing undergraduate Mathematics students’ research worked with the University Archives to arrange and describe Kenneth Appel’s personal papers. In 1976, Kenneth Appel and his colleague Wolfgang Haken (both Mathematics faculty members at the University of Illinois), succeeded in proving the “Four-Color Theorem.” This theorem argues that every map in a plane or a sphere can be colored with only 4 colors in such a way that no two countries of the same color are touching. By that time, mathematicians had been working to prove this theory for over one hundred years. In fact, it took hundreds of hours of computing work for Appel and Haken to prove it. The announcement that the theory had been proven was met with a flood of people writing to them. Some were writing to congratulate the team and others to prove the team wrong.

The students worked alongside the archives staff to learn more about the archival process by appraising the material, arranging and describing it, and rehousing the materials in archival boxes, all while taking an historical approach to mathematics, using primary sources to learn more about Appel, his research, and the ways in which the mathematics community reacted to what was then a controversial finding. Kenneth Appel’s Papers include correspondence relating to the Four-Color Theorem that illustrates both in number and in tone, the storm of letters that Appel and Haken were bombarded with at the time. Some notable letters include a teacher that says his eighth graders were able to prove the theory wrong and an account of a $100 bet that was made that the theory could not be solved by July 1976, including a photocopy of the $104 dollar check (the four dollars being paid for “interest”). The record series also includes publicity materials, drafts of papers, and data printouts and computer punch cards, much of which relates to the Four-Color Theorem.

On Saturday, November 4, 2017, the students will host an exhibit featuring materials from the collection. The exhibit will be a part of the Illinois Geometry Lab Open House which is being held in conjunction with the Department of Mathematics’ Four Color Fest, an event being held to celebrate the 40th anniversary of the proof.

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