MATLAB Programming Contest

Addictive Collaboration

Patterns of Participation in an Open Programming Contest

Ned GulleyThe MathWorks, Inc.

Competitive Wikipedia

MATLAB Programming Contest:

A week-long open collaborative competition for MATLAB programmers

• Entries are automatically scored, ranked, and displayed immediately

• Code, author, and score are visible at all times

• Anyone can modify anyone else's code and resubmit it as their own

Protein folding

leaders

leaders

1 karim2 carol3 eric karim.

fcn f(x)...

view entry

new entry

ned.fcn f(x)...

1 ned2 karim3 carol4 eric

Doug says:

“I do not understand why anyone would be interested in participating in a contest where a winning idea is immediately co-opted and tweaked by another player.”

Stijn says:

“I started Monday after work. I worked late, let's say 4 or 5 hours. I started to become ‘obsessed’. At home, although I am a father of three children, my full-time job was working on the contest. I didn't sleep much. I worked maybe 10 hours after work each day. On Thursday it was clear that I wasn't going to be able to work seriously (for my job), so I took a day off on Friday.”

“This is my first MATLAB contest and it is giving me far too much enjoyment. It's one of the most addictive things I have tried. The exercise is improving my programming skill, but in return I have backache, a terrible diet, no social life, and not much of a work life either. Also, I have experienced physical trembling while making the final preparations to send a code into the pit. Is that normal?”

Nathan says:

Patterns ofParticipation

Big changes (Leaps)

function f = fb(n)a = [0 1; 1 1]^n;f = a(2);

function f = fb(n)if n > 2 f = fb(n-1) + fb(n-2); else f = 1; end

Generating the nth Fibonacci number: 1, 1, 2, 3, 5, 8, 13, ...

Small changes (Tweaks)

...y = [1 2 3]...

...y = 1:3;...

Better

Time

Wednesday Monday

Score = k1 * (algorithmic result) + k2 * (CPU time)

Punctuatedequilibrium

(the zigzag of innovation)

CPU Time

CostFunction

CostFunction

CPUTime

CostFunction

CPUTime

Collaboration

Code Market Share by Line Count

Schools of thought(clans)

Innovation uptake

First use of

conv

First leader

with conv

Systematic variation(tweak bombs)

Social signaling

• Scrambled Eggs• Rotten Eggs• I didn't start the fire• don't get obfuscated ... follow the light• You Call This Collaboration? Give

Me A Break

• Tweak Tweak Tweak• tweakfest • tweak-o-rama• slippery ground (tweak me)• Seems like everyone's just tweaking• I said to myself not to do this kind of

thing...• Poopdeck Pappy gives in to peer

pressure

• I wish I knew how this works

Phase transitions

novel

conserved

deleted

Line-by-lineAnalysis

History Flow

Knapsack, all

Knapsack, leaders only

Knapsack leaders

Knapsack shortest path

The shortest path

Two views of history

Broad variations

Deep variations

Motivation

Personal gloryor

Collaboration ?

Behavior of a jealous coder

• Last-minute entry• Obfuscation• Spaghetti code• No comments• Sandbagging• Sock puppeting• Combinations

“Behavior” of successful code

• High rank• Time on top• High status

author• Clarity• Elegance• Comments• Novelty

The code wants to propagate!

The coder wants to block code propagation

The essential tension:

For the code • Encourage copying• Highlight changes• Punish complexity• Discourage

obfuscation• Easy tweaking

For the coder • Make participation

easy• Reward vanity• Many cheap prizes• Darkness period• Easy tweaking

Managing the tension:

A chicken is only an egg’s way of making another egg.

A hacker is only code’s way of

making more code.