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4 color maps

  1. Jul 16, 2013 #1
    while it has been extensively proven that any 2D map can be colored with at most 4 colors, has any hypothesized why that is (outside the computer programmed brute force method)?
  2. jcsd
  3. Jul 16, 2013 #2
    I think I can see it just by doodling.Sketch a map with three regions and needing three colours.The shapes and sizes of the regions and the overlap borders are irrelevant. Now add a fourth region which borders the first three regions and you will see that this fourth region must completely surround at least one of the other three regions.
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