Can the set of lattice points be colored using 10 distinct colors such that for all , the colors of and are distinct?
Solution
Yes. Associate to each number from 1 to 252 a distinct 5 -element subset of . Then assign to an element of that is in the subset associated to but not in that associated to . It's not difficult to see that this numerical assignment is a valid coloring: the color assigned to is not in , while the color assigned to is in , so they must be distinct.
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