MathDB

4

Part of 2014 Switzerland - Final Round

Problems(1)

a x b colors on infinite grid

Source: Switzerland - 2014 Swiss MO Final Round p4

1/14/2023
The checkered plane (infinitely large house paper) is given. For which pairs (a,, b) one can color each of the squares with one of a⋅ba \cdot b colors, so that each rectangle of size a×b a \times b or b×ab \times a, placed appropriately in the checkered plane, always contains a unit square with each color ?
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