RIP to the man who started me down the path of a career in computer science… I still have a signed copy of his proof back at home…

Brilliant:

Their conclusion, that four colors would suffice for any map, depended on 1,200 hours of computer time — the equivalent of 50 days — and 10 billion logical decisions all made automatically and out of sight by the innards of an I.B.M. computer at the University of Illinois in Urbana.

Hailed in some circles, including this newspaper, as “a major intellectual feat,” the proof shepherded computers toward a greater role in higher math. But it made many mathematicians uneasy; they worried about computer bugs and wondered how they could check or understand a “proof” they could not see. And it ignited a long-running debate about what constitutes a mathematical proof.