Etiquette Algorithms
↓ Updated: September 2nd, 2009.
Elevator Etiquette
I have spent a fair amount of time in elevators over the course of my life. Elevators are awkward places to be. You look at the ceiling, check your watch, and you definitely don’t make eye contact. If you know someone in the elevator it’s probably just as bad. Odds are it’s someone you don’t see often, which means you are forced to make small talk for the remainder of the ride. No fun.
There’s another thing that happens on elevators. You move around to maintain your personal space as people get on and off. Its an algorithm that’s pretty well defined, and everyone seems to know it, although no one ever talks about it. Because I think about this stuff a lot, I’ve decided to try and codify it. This is what happens when a person (let’s call him person a) enters the elevator:
if (elevator is empty)
stand anywhere on the perimeter
else
if (distance between people along the perimeter > perimeter threshold)
person a stands on the perimeter
everyone else moves along the perimeter to equalize distance between people
else
person a stands near entrance
everyone else moves along the perimeter to maximize the approximately
circular area surrounding them
The algorithm is pretty simple. The idea is to maximize the area that surrounds you with a caveat. That caveat is that it seems desirable to have everyone stand on the perimeter, to a point where that can be more important than maximizing your space. This is done until some threshold distance between each person along the perimeter (let’s call it the perimeter threshold) is crossed and everyone in the elevator begins to spread out over the entire area. This seems to happen pretty regularly and accurately and everyone just seems to know how its done.
Urinal Etiquette
There’s another etiquette algorithm that I know about. This one is exclusive to men and involves deciding which urinal to use in a row of urinals. Here’s how I see it:
if (bathroom is empty)
pick a urinal close to the ends of the row
else if (urinals have dividers)
if (urinal use ratio < 0.2)
pick a urinal at least 2 spaces away
else
pick any urinal, with preference given to urinals are flanked
by at least one empty one
else
if (urinal use ratio < 0.2)
pick a urinal at least 6 spaces away
else
if (there are urinals that are flanked by two empty ones)
pick one
else
if (you really have to go or you have little shame)
pick any urinal
else
wait it out until there is a urinal available that is flanked by two
empty ones and then use it
Send me your corrections and comments. I bet the algorithms are a bit more nuanced than this. Are there any other algorithms that we all just know? I can’t think of any more off the top of my head, but I’m sure there are some.
Update: Randall Munroe of XKCD fame has a rather thorough discussion of the urinal problem that is really worth reading. ↑
Phil — Apr 13th 3:13pm
http://www.albinoblacksheep.com/flash/urinal
David — Apr 13th 3:16pm
Ha, some things in that game I hadn’t thought about yet.
Mike — Apr 13th 6:17pm
As is, your elevator algorithm will run more or less smoothly up to elevator capacity. But to more closely simulate reality, we might allow riders to hold independent threshold values. Normally distributed, social tensions would still likely be held to reasonable levels – at least until probabilistically reaching that rare individual with an extreme minimum threshold entirely inconsistent with the rest of society.
Or, someone steps in and faces the back wall of the elevator.
Conventional protocol offers no solutions to handle these crazies.
Gab — Apr 13th 6:28pm
state your assumptions: “at least six spaces” makes it sound like we are in a stadium.
Katie — Apr 17th 3:00pm
I think it should be the case that urinal etiquette applies to stalls as well, but in a looser sense. There are probably around 8 stalls in the ladies room at work, and I find it unnecessarily uncomfortable for someone to use the one next to me if others are unoccupied. Though I can understand that often times people do this unintentionally. Of course, in this case, one buffer stall is almost equivalent to many buffer stalls until the number of stalls gets quite high, so maybe it’s more analogous to the etiquette for seats on the subway.