Doesn't Bell Labs have a patent on a solution to this problem or a close variant?
---
If you have an unlimited amount of patch cord, why not simply
bury that and lose the cable? Only one 10 mile walk is required, carrying
or pushing the cable reel.
On second thought, 10 miles of optical fiber doesn't weight very much, so bury
that instead -- it has thousands of times the bandwidth of the 120 individual
wires.
At 06:55 AM 7/17/2006, Michael Kleber wrote:
>A week or two ago I heard for the first time the following
>enjoyable brain teaser:
>
>---------
>A company has just buried a 10-mile-long cable containing
>120 individual wires. Unfortunately, the project was overseen
>by a summer intern, and the sad result is that the wires are
>entirely unlabelled. Your job is to fix this mess: label each
>wire with the same name on both ends.
>
>The tools you have available are (1) a battery, (2) a lightbulb,
>and (3) an unlimited amount of patch cord. And (4) your feet,
>and no other form of transportation. You start at one end of
>the cable, and can do as much as you want there, but then
>you need to walk down to the other end and repeat.
>
>In how few trips down the length of the cable can you label
>the wires?
>---------
>
>I have a second problem for follow-up, but I can only present
>it to people who have solved the first problem (for general n,
>of course, not just n=120). So tune in tomorrow for my tale of
>the ups and downs in solving this one, and perhaps help me
>out of my end state (down).
>
>--Michael Kleber
>
>p.s.: An interesting observation is that with n=2 the problem
>is unsolvable; there is no way to tell the two wires apart.
>
>--
>It is very dark and after 2000.
>If you continue you are likely to be eaten by a bleen.
