A fact from Distinguishing coloring appeared on Wikipedia's Main Page in the Did you know column on 19 August 2015 (check views). The text of the entry was as follows:
Did you know... that six or more keys on a keyring can be distinguished from each other by coloring the keys using only two colors, but rings of fewer keys require more colors?
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Can someone please dumb this article down a bit? For example: In the photograph that accompanies this article, how does one distinguish the three red keys from each other? Maybe I don't understand what "distinguish" means in this context? --Keeves (talk) 16:54, 19 August 2015 (UTC)[reply]
For the keys it is not just the colour, but also the position on the keyring relative to the other keys. Key 1 is red and next to one plain key on one side and two on the other (because it is a closed loop, Key 6 is on the other side of Key 1); Key 2 is plain and next to a red key on both sides; Key 3 is red and next to one plain key and one red key; Key 4 is red and next to one red key on one side and two plain keys on the other, etc. Any key you pick is in a unique sequence of coloured keys. (Brought to you by Belle's Brilliant Brain: getting maths wrong since 19+80) Belle (talk) 17:28, 19 August 2015 (UTC)[reply]
I added the sentence "With such a coloring, each key will be uniquely identified by the sequence of colors surrounding it." Does that help? —David Eppstein (talk) 17:40, 19 August 2015 (UTC)[reply]
