April 30, 2013 at 1:28 PM ET
Kenneth Appel was a mathematician who embraced early on the capabilities of computer calculation, solving a century-old problem with a program when such a thing was unheard-of. He helped break the ice between academics and the computing world, presaging today's era of digital scholarship.
Appel, born in Brooklyn in 1932, collaborated with Dr. Wolfgang Haken to prove what's known as the "Four-color theorem," which states that four colors are enough to fill in any map without any two regions of the same color touching. Although first proposed in 1852, the proof had eluded mathematicians for a hundred years; Appel and Haken felt that the power of computers was just the solution.
They obtained their proof by using an early IBM owned by the University of Illinois to run through thousands of configurations, using 1200 hours of computer time and necessitating days of checking by hand the computed results. But in the end, the proof was sound.
That didn't stop mathematicians from attacking the proof as incomplete, although to this day no flaws have been found. And while these objectors may even today prefer the methods of classic mathematicians, Appel and Haken were only the first in a long line of academics whose proofs and other scientific work would be enabled by computers. There was, in fact, as Appel observed, a whole class of problems that were only realistically solvable by computers.
Appel died of esophageal cancer on April 19. He is survived by his wife, daughter, two sons, and five grandchildren.
Devin Coldewey is a contributing writer for NBC News Digital. His personal website is coldewey.cc.