Puzzles I worked on (MIT Mystery Hunt 2013)

Quick summary of MIT Mystery Hunt 2013 — didn't work on as many puzzles this year, between (a) Not Trying To Win (after writing last year's hunt), and (b) Zachary. Did quite a bit of work on the hunt-solving software; discovered that the current limits to Meteor's scalability are "less than team Codex".

Puzzles I particularly liked:

• Time Conundrum (except for final extraction)
• Too Many Seacrests
• Tuva or Bust (for which I successfully used Prolog in anger)

Other puzzles i worked on:

• Square Routes
• The Maze (helped guide final extraction)
• Czar Cycle (which we never solved)
• Road Trip (final extraction, with alexp)
• Space Monkey Mafia (final extraction, with alexp)
• Diagramless Crossmusic (knew how it worked, but meh)

There were a lot of very interesting puzzle ideas in this hunt. Several of them would have made excellent puzzles, given a bit more focused editing. In particular I want to single out 50/50 and Diagramless Crossmusic as great ideas.

Thanks to the Sages for all their work over the past year. The Mystery Hunt is a ton of work to write, and it's all done for the love of the thing.

Syndicated 2013-01-25 04:16:28 from Dr. C. Scott Ananian

The Gashly-Hunt Tinies (MIT Mystery Hunt 2013)

A is for ADPHI, who ran out of Rs, B is for Better Luck assaulted by czars.
C is for Codex who expired half way, D is for Dataviz stumped by “Wordplay”.
E is for Eigenpirates who left for the beach, F is for Fangorn’s chaotic speech.
G is for Grand Unified Theory’s lost love, H is for herrings caught shifting through drugs.
I is for Illegal, Immoral, and awake; J is for Jones who plagued teams with hard snakes.
K is for Keypad which we did without, L is for Left—as an exercise or just out.
M is for Meteor misstressing trochee; N is for Ninjas searching etsy.
O is for Om Nom locked out of the vault; P is for Part blah blah Who is John Galt?
Q is for Quadragesima Magna Victi In Cratera; R is for Raucous collecting old lira.
S is for Setec humming tunes with 8-bits; T is for Too Long spent reading git hub commits.
U is for Unseen who got caught Up Late; V is for Victory after seventy hours straight.
W is for White Magic which we never solved; X is for Xerox: conundrums resolved.
Y is for You Not Going to Space; Z is for Zero hunts matching this pace.


AdPhi and Better Luck This Time are team names. “Czar Cycle” was a difficult puzzle involving the Cyrillic, Greek, and Roman alphabets.
Codex Zouche-Nuttall and Dataviz are team names. “Wordplay” was a cryptic crossword.
Eigenpirates and Fangorn Foureast are team names. “Chaotic speech” is a reference to the “Grandson of the Realm of Unspeakable Chaos”
Grand Unified Theory of Love is a team name. “Substance Abuse” was a puzzle involving caesar-shifted chemical names.
Illegal, Immoral, & Fattening is a team name. Indiana Jones was the name of a round whose metas involve solving very difficult snake puzzles, resulting in 3d knots which then needed to be identified.
Keypad was the name of the obstacle corresponding to the Erno Rubik round. Left Out and Left As An Exercise For The Reader are team names.
Meteor Lab is a team name. ”Trochees, etc“ was a puzzle involving trochees (pairs of syllables with the first accented, as trochee itself should properly be) and etsy.com
Om Nom Nom is a team name, as is the complete text of Atlas Shrugged, which starts with, "PART I: NON-CONTRADICTION; CHAPTER I: THE THEME 'Who is John Galt?'..."
“VICTI IN CRATERA MAGNA QUADRAGESIMA”,or “conquered in the great/super bowl 40” (ie, SEAHAWKS) was the final cluephrase in the puzzle “Caesar's Palace”. Raucous Raucous Rhinos is a team name. “Collecting old lira” refers to the scavenger hunt puzzle "De-Coins".
Unseen Gambit and Up Late are team names. Seventy hours is a very conservative estimate of hunt length, from a 2pm start on Friday to a noon Monday commencement of the final runaround.
White Magic was a meta puzzle in the Erno Rubik round. The Xerox machine featured prominently in the “Time Conundrum” puzzle, used to create another copy of the instructions so that the first could be sent back in time with the correct answer written on it...
“You Are Not Going To Space Today” was a first-round puzzle. This hunt was the longest hunt ever.

Syndicated 2013-01-23 00:37:10 (Updated 2013-01-23 23:19:46) from Dr. C. Scott Ananian

SDR 0.7

Happy Thanksgiving! Here's SDR 0.7 to celebrate the holiday. Version 0.7 incorporates a number of dance engine refactorings completed shortly after the previous release promised them, as well as (more recently) a number of new call and concept definitions (and test cases) inspired by the C4 calls I am currently studying. I also updated Google App Engine and Google Web Toolkit to the latest versions for the web app, although jMonkeyEngine is still stuck at 2.0 — we might get an Android version of SDR if I manage to rebase to jMonkeyEngine 3.0 for the next release.

Breathing the square properly is still a challenge. Other square dance programs only treat starting and ending formations, but SDR has to consider all of the intermediate positions along the dancers' paths. This leads to some very unusual formations being breathed. As mentioned in the notes for the last release, SDR formulates breathing as a solution to a mixed integer linear programming problem—but there are still a few bugs lurking which cause the constraint solver to blow up from time to time (especially from columns, for some reason). Hopefully I'll be able to dig into this for the next release.

Syndicated 2012-11-22 19:29:56 from Dr. C. Scott Ananian

Reading Project Talk (and slides)

An unruly tag team of OLPC folks gave a long talk on the Literacy Project today for attendees at this year's OLPC-SF Community Summit. It was streamed live on Ustream: Part 1 (Matt Keller, Richard Smith), Part 2 (Richard Smith, Ed McNierney, C. Scott Ananian, Chris Ball, questions from the audience). We've posted the slides: Matt Keller, Richard Smith, C. Scott Ananian.

You can try out some of the apps mentioned in the talk. Nell's Balloons and Nell's Colors will run in any reasonably-recent Google Chrome or Mozilla Firefox browser. They will also run as a Firefox webapp on Android devices, using the latest Firefox nightly for Android. For deployment we use a slightly-tweaked build of Firefox (adding expanded webapp storage quotas and the ability to use plugins from inside webapps), and a custom plugin to hook up the Funf logging framework. Source code is available on github: nell-balloons; nell-colors. In addition, Chris Ball's "Matching" app for Android is available: apk; source.

Syndicated 2012-10-21 22:51:05 from Dr. C. Scott Ananian

The Importance of Sensing Distance

At IDC 2012 in June, Arnan Sipitakiat and Nusarin Nusen discussed how they are using Robo-Blocks—a turtle robot and “tangible Turtle Blocks”—to teach problem solving and debugging skills to 5- through 12-year-olds.

One of the things I learned from their presentation was that children had difficulty reasoning about relative angles. The Robo-Blocks robot does not have any distance feedback on its motors, so “the result of a program will change depending on the roughness of the surface and the battery level of the robot.” They worked around this issue by developing a protractor tool to guide the children's reasoning about the relationship between the (arbitrary) numbers entered and the amount the robot turned, but some kids still had difficulty. The researchers “often had to insist on trying the protractor” and “some children preferred to keep increasing the turn amount even if a small decrease would have fixed the problem” resulting in programs that had the robot making multiple complete rotations before setting off in the correct direction. The kids were also dissatisfied with polygon-drawing tasks (“turtle geometry”) because the inaccuracies of open-loop control of the robot means that the polygons often didn't close completely, and “[t]his small error turned out to be unacceptable to children.”

So I designed the XOrduino turtle robot from the start to have distance sensors so that it can do accurate turns with closed-loop control. Here's a little video showing how they work in the current (A1.5 / B1) revision of the board: