In the 1970s, for example, a computer played a major role in settling the proof of the Four-Color Theorem, which had gone unsolved for over a century. This problem theorized that, if you wanted to illustrate a map—perhaps of Europe but really of any region actual or fictional—so that no two countries that shared a border were shown in the same color, you would need no more than four colors in total. Some maps could be executed in just three colors, but in no case would a fifth color be required. Already, the proof had been constructed for the claim that five colors would suffice, but before
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