Git Hub (Solution)

by Rob Speer

The trick

This is a Git repository whose history graph is isomorphic to the MBTA subway map.

Every change in the repository replaces some fragment of fake Latin text with arbitrary English words of the same lengths. The words sometimes repeat, because they are a code for the names of the subway stops, each word also matching a word of the same length. For example, "CENTRAL" changes some 7-letter Latin word to "angling", even if it appears in a longer station name such as "BOSTON UNIVERSITY CENTRAL" or "CENTRAL AVE".

The "initial state" is State Street.

Finding the commits

If you look at the repository you're given, you find a very short path of unnamed commits from "master" to "initial state". The location of "master" (which is your current HEAD) is Kendall/MIT, and what you're seeing is the two routes from Kendall back to State.

There are lots of other commits in the repository; they're in other branches.

Now you've got a graph you can explore. gitk --all will even show it to you, as a kind of tangled mess. Drawing it on paper may help. You need to match the commits to T stations, with the word lengths and the code as a check to make sure you're in the right place.


12 of the commits have messages that look like this:

_ _ _ _ ? _ _

The blanks match the lengths of the words being replaced. Match them to the replaced Latin words and you get gibberish. Match them to the English words that replace them and you get NOTTHEANSWER. But match them to the names of the T stations, and you get:


This is why the replacement words were in English: two of them contain the answer. Find the stops with these words in the name (QUINCY ADAMS and ALLSTON ST), and find out what they encode to. ADAMS ALLSTON is code for SCOUT NETWORK, which is the answer to the puzzle.

Arbitrary decisions

Faced with the decision on how to encode very similar words like CENTER/CENTRE/CENTRAL, HILL/HILLS, and ST/STREET, I decided to have them also encode to very similar words. For example, CENTER, CENTRE, and CENTRAL become ANGLES, ANGELS, and ANGLING respectively. This kind of allows for disagreements in spelling.

The English words are almost meaningless. In a few cases I tried to make them hint at the fact that the words don't matter, such as "ST MARYS ST" becoming "be noisy be", "BOSTON UNIVERSITY EAST" becoming "fairly irrelevant text", and "CEDAR GROVE" turning the initial "Lorem ipsum" into "silly words". There are a couple of hints like "BACK OF THE HILL" becoming "look at git tree" and "BACK BAY" becoming "look hub".

The other words are totally arbitrary moderately-frequent English words, tweaked a bit to spell NOTTHEANSWER when you don't use the T station names.

The initial letters of the English replacement phrases on the northbound Red line spell RED HERRI(N|G). Though in the initial setup, you can only see the RRI(N|G) part.

Git commits contain lots of information, pretty much all of which are irrelevant to this puzzle. The author and committer are "Manic Sages". They commit with timestamps of 2013-01-18T12:xx:00, where xx is an optimistic estimate of how many minutes it would take to get to that station from State Street. I used for the timing here.