Author Archives: Harmen
Reality on the Norm 054: Before the Legacy
Reality on the Norm 052: MI5 Bob
Reality on the Norm 051: Shadows of RON
Reality on the Norm 044: A Better Mouse Trap
Reality on the Norm 043: The Phantom Inheritence
Reality on the Norm 042: Koalas and Con-men and Krakens and Catholics and Kerfuffles and Chicanery and Kayaks and Codeine and Knapweed. And Cossaks.
Reality on the Norm 040: Purity of the Surf
Reality on the Norm 038: Defender of RON
Reality on the Norm 037: The Underworld
Reality on the Norm 036: The Tapestry
Reality on the Norm 033: Kittens and Cacti
Reality on the Norm 031: Cabbages and Kings
Reality on the Norm 030: Intergalactic Life 2.0
Reality on the Norm 028: The Chef
Schelling’s model of segregation
A little bit of a preference goes a long way
As the saying goes: “birds of a feather flock together”. People with similar backgrounds tend to end up in the same social group. This effect can be so extreme that it eventually leads to the kind of segregation in which the only people of the same background interact with each other. But how much of such a “preference for similarity” is needed to get a segregated society? In 1971, Thomas Schelling tried to answer this question using multi-agent simulations (Schelling, 1971). The script on this page (open script in separate tab) shows an implementation of Schelling’s model of segregation. The controls for this script are outlined at the bottom of the page.
The JavaScript on this page makes use of HTML5.
AgentVille supporters
The script on this page simulates how segregation occurs on the bleachers of AgentVille. The fictional town of AgentVille is known for its annual sports event, which draws many supporters of both Team Orange and Team Blue. When a supporter arrives at the stadium, he randomly decides where to sit and watch the event. But that does not mean that AgentVille supporters have no preferences on where they want to sit. Each supporter wants to sit close to someone that supports the same team. In fact, each supporter agent wants that among neighboring seats, there is some minimum percentage of people that supports the same team as he does. The way this works is demonstrated in Figure 1. As you can see by moving the agents around these nine spaces, each supporter agent has up to eight neighboring seats. An agent only shows a wide grin of happiness when at least 50% of the people in these neighboring seats supports his team.
Figure 1: Agents want to have a minimum percentage (50% in this case) of people in neighboring seats to support the same team as they do. In this interactive figure, you can drag agents to a new position to see how this works. Only happy supporters show a wide grin. |
The pursuit of happiness
If a supporter is unhappy with his seat, he will eventually get up and move to one of the empty seats. It is not hard to see that if every agent demands that 100% of the people in neighboring seats supports the same team as he does, this process of switching seats will only stop when the supporters for both teams are completely separated. But does a lower similarity preference also cause segregation on the bleachers? Is the number of empty seats important? If each supporter wants 50% of his neighbours to support their team, will the average similarity be 50% when all supporters are happy, or would it be much higher?
The script on this page allows you to play around with different situations on the bleachers and see what will happen to the way supporters seat themselves. The graph keeps track of the number of happy supporters (green line) and the average percentage of people in neighboring seats that support the same team (red line). One thing you may want to keep an eye on, is the difference between the preferences of individual supporters (as shown by the desired similarity slider) and what the average similarity of neighboring supporters ends up being.
Controls
- Support agents on the bleachers: You can manually drag agents to empty seats. An agent that is happy with his current situation will show a broad grin. Agents without such a grin will eventually want to move to another seat.
- Happiness / similarity graph: After every change in the situation on the bleachers, the graph shows the current percentage of agents that is happy (green) and the average percentage of agents in neighboring seats that support the same team (red).
- Number of agents slider: This determines the number of agents trying to find a spot on the bleachers. There are 200 seats available, and the number of agents can vary between 1 and If the number of agents is even, there will be as many Blue Team supporters as Orange Team supporters. If the number of agents is odd, there will be one more supporter for Orange Team.
- Desired similarity slider: This slider determines for each agent what percentage of neighoring agents that support the same team will make him happy. All agents have exactly the same desired similarity.
- Simulation speed slider: This shows how quickly changes occur on the bleachers, varying from one change per second to up to 2500 changes per second.
- Start/stop simulation: The simulation will automatically stop when 100% of agents is happy. Starting the simulation does not reset the board. This means you can pause the simulation to make some manual changes if you want, and continue from the situation you have created.
- Reset field: Removes all agents from the board and lets each of them choose a new seat.
Reality on the Norm 029: Toxically Earth
Reality on the Norm 026: Intergalactic Life
Reality on the Norm 024: Davy Jones is back
Reality on the Norm 021: Strange Days
Reality on the Norm 020: The Punk Allen Trilogy
Reality on the Norm 019: Scoop Da Poop
Reality on the Norm 018: Your Bum Is Talking
Reality on the Norm 017: Hooky McPegleg: Pirate Postman!
Reality on the Norm 016: I Spy II
Reality on the Norm 015: Monty on the Norm
Reality on the Norm 014: Paranormal Investigation
Reality on the Norm 013: The Lost Treasure of RON
Reality on the Norm 012: The Postman Only Dies Once
Reality on the Norm 009: The Repossessor
Reality on the Norm 008: Edge of Reality, Part 1
Reality on the Norm 007: Blast Off
Reality on the Norm 006: Return of Dee Vie Ess
Reality on the Norm 004: I Spy
Reality on the Norm 003: The Soviet Union Strikes Again
Reality on the Norm 002.5: Fowl Play
Reality on the Norm 002: Vengeance on the Chicken
Reality on the Norm 001: Lunchtime of the Damned
Quest for Glory I: So You Want To Be A Hero?
Questprobe 3: The Fantastic Four
Questprobe 2: Spiderman
Questprobe 1: The Hulk
Project Xenophobe
Prodigal
Police Quest 4: Open Season
Police Quest 3: The Kindred

Ticket codes for writing tickets are available from the game manual. [+] Locker code: 776 Open the western blue door. Take the form from the basket on your desk. Walk southeast, northeast, through the open door. Talk to Morales. Take the clipboard. Walk northeast, northwest. Open the western blue door. Determine the complaint is sustained. Take the form from the basket on your desk. Walk southeast. Use the elevator button. Go to the first floor. Open the locker. Take some road flares. Take some batteries. Walk into the mens locker room. Open the locker in the middle. Take the notebook. Take the nightstick. Take the flashlight. Use the batteries with the flashlight. Close the locker. Walk northwest. Use the elevator button. Go to the third floor. Give the form to the man. Take the card. Use the elevator button. Go to the second floor. Open the western blue door. Wait until the message to call dispatch comes in. Use the phone. Pick up the receiver and call dispatch. Walk southeast. Use the elevator button. Go to the ground level. Use the squad car’s door. Drive to Aspen Falls. Walk east. Talk to the man. Walk to the man. Search the clothes. Use the keys with the water. Use the nightstick with the man. Use the handcuffs with the man. Search the man. Open the passenger’s door. Use the squad car. Drive to the police office. Open the top left locker. Put the gun in the locker. Walk northeast. Use the license with the drawer. Use the knife with the drawer. Use the door. Book Forbes for possession of a concealed weapon. [+] Take the handcuffs from the drawer. Walk southwest. Use the locker key with the top left locker. Take the gun. Use the squad car. Drive on the ramp of the highway at 7th street. Drive until you reach Morales. Talk to Morales. Talk to the driver of the car. Talk to Morales. Witness the refusal to sign. Use the squad car. Patrol the highway. You’ll encounter a black car speeding.
Turn on the sirenes. Speed up and drive besides the car. Look at the car. Use the computer, and enter the plate number (12896). Quit the computer. Turn off the sirenes.
You’ll encounter a white car speeding.
Turn on the sirenes. Speed up and pull the car over. Take note of the military time onscreen. Walk around the right side of the car to the driver. Talk to the driver. Look at the car’s plates. Use the squad car. Use the license on with the machine. Look up the plate number of the car (34567). Make out a form 900. Enter the correct military time. Enter the vehicle code for exceeding the maximum speed limit. [+] Take the ticket. Leave the car. Walk around the right side of the car to the driver. Give the ticket to Orpheus.
You’ll encounter a slow car in the fast lane.
Turn on the sirenes. Pull the car over by driving to the right and behind it. Take note of the military time onscreen. Walk around the right side of the car to the driver. Talk to the driver. Look at the car’s plates. Use the squad car. Use the license with the machine. Look up the plate number of the car (22776). Make out a form 900. Enter the correct military time. Enter the vehicle code for driving too slow in the fast lane. [+] Take the ticket. Leave the car. Walk around the right side of the car to the driver. Give the ticket to Ruiz.
Patrol until you meet a swirving car.
Pull over the car. Walk around the right side of the car to the driver. Talk to the driver. Talk to the drunken driver. Move your finger from side to side. Talk to the drunk. Search the drunk. Use the handcuffs with the drunk. Use the drunk. Use the squad car. Drive to the police office. Open the top left locker. Put the gun in the locker. Walk northeast. Take the handcuffs from the man. Open the drawer. Use the breath analyser. Turn the machine on. Take the pipe. Take the alcohol outcome note. Use the door. Book the man for driving under influence. [+] Walk southwest. Use the locker key with the top left locker. Take the gun. Use the elevator button. Go to the second floor. Open the western blue door. Use the phone. Pick up the receiver and call dispatch. Walk southeast. Use the elevator button. Go to ground level. Use the squad car. Drive to Oak Tree Mall. Take the chain from Marie’s hand. Walk southeast. Talk to the reporter. Use the flashlight with the ground. Walk along the car. Pick up the bronze star. Look at the star and note the number. Use the squad car. Take the music box. Walk south. Use the elevator button. Go to the second floor. Open the eastern door. Use the computer. Use the access card with the card slot. Review Homicide cases 199144 and 199137. Look up the Bronze Star serial number (09987). Review case 199124. Look at the business card. Use the phone. Pick up the receiver and dial the reporter’s number (555-0707). Open the door. Use the elevator button. Go to ground level. Open the door. Use the Bonze Star with the evidence drawer. Book the Bonze Star under case 199144. Use the chain with the evidence drawer. Book the chain under case 199144. Walk to the flower shop. Talk to the florist. Use the wallet with the florist. Talk to the secretary. Use the elevator button. Talk to Marie. Give the music box to Marie. Give the rose to Marie. Kiss Marie. Walk southeast, northeast. Use the elevator button. Go to the second floor. Use the eastern door. Take the note from the basket on your desk. Open the door. Use the elevator button. Go to ground level. Use the unmarked car. Go to the southern part of second street. Talk to the woman. Use the badge with the woman. Talk to the woman. Use the handcuffs with the cart. Talk to the woman. Take the lunch. Use the computer. Use the card with the computer. Use the Drawing Composite in the Tools menu. Follow the directions of the woman. Complete the composition drawing. Search for matches. Read the file on the man. Shut down the computer. Talk to the woman. Take the handcuffs from the cart. Use the car. Wait until Pat returns. Use the elevator button. Go to the second floor. Open the eastern door. Take the note from the basket on your desk. Open the door. Use the elevator button. Go to ground level. Use the squad car. Open the glove compartment. Take the speed calibration chart. Leave the car. Use the unmarked car. Drive to court. 8th Rose Walk northwest. Talk to the District Attorney. Talk to the District Attorney. Give the speed calibration chart to the District Attorney. Use the car. Take the key from the purse. Leave the car. Enter the western shop. Give the key to the keymaker. Pay the keymaker. Use the car. Use the keys with the purse. Drive to Rose, 300 block. Open the trunk. Put the flares in the box. Open the case. Take the scraper. Take the bags. Take the toothpicks. Close the case and the trunk. Look at the body. Search the trousers. Use the identity papers with the notebook. Look at the hands. Use the toothpicks with the victim’s nails. Remove the shirt. Use the notebook with the body. Leave the body. Look at the car. Use the scraper with the gold paint. Open the trunk and the case. Put the toothpicks in the case. Put the bags in the case. Put the scraper in the case. Close the case and the trunk. Use the car. Drive to the police office. Use the elevator button. Go to the second floor. Open the eastern door. Take the note from the basket with your desk. Use the computer. Put the card in the computer. Make a new Homicide case. Leave the computer. Use the copied key with Morales’ desk. Read the piece of paper. Close the drawer. Open the door. Use the elevator button. Go to ground level. Open the door. Use the hair and skin samples with the drawer. Book the hair and skin samples on case 199145. Use the car paint with the drawer. Book the car paint on case 199145. Walk southwest. Use the unmarked car. Drive to the hospital. Use the elevator button. Take the clipboard. Look at Marie. Look at the IV dosage. Use the button. Leave Marie. Wait until the nurse appears. Talk to the nurse. Walk southeast, northeast. Use the elevator button. Go to the second floor. Open the eastern door. Look at the bulletin board. Talk to the man. Use the computer. Use the access card with the computer. Review the four relevant homicide cases 199124, 199137, 199144 and 199145. Take note of their locations. Use the City map tool. Place a point at 392 S 6th street. Place a point at 280 W Palm. Place a point at 341 E Rose. Place a point at 376 W Rose. Use the check pattern to make a pentagram. Leave the computer. Use the phone. Pick up the receiver and call dispatch. Open the door. Walk east. Open the eastern door. Pick up the psychologists’ file. Walk south, west. Use the elevator button. Go to the third floor. Use the desk. Take the tracking device. Use the elevator button. Go to ground level. Use the unmarked car. Drive to the missing pentagram location (200 E Palms). Look at the car. Open the trunk and the case. Take the scraper. Take the bags. Use the scraper with the car. Use the tracking device with the car. Open the door. Wait until the second billiard player arrives. Talk to the billiard player in black. Return fire at the suspect. Turn on the tracking device. Pursue the suspect until he crashes. Drive to the crash site. Open the trunk. Take the flares. Close the trunk. Use the flares with the road. Look at the body. Take the keys. Search the body. Talk to the medics. Use the keys with the trunk. Take the cocaine bags. Drive to the police office. Open the trunk and the case. Put the bags in the case. Put the scraper in the case. Close the case and the trunk. Use the elevator button. Go to the second floor. Open the eastern door. Take the note from the basket on your desk. Open the door. Use the elevator door. Go to ground level. Open the door. Use the scrapings with the drawer. Book the scrapings on case 199145. Walk southwest. Use the car. Drive to the hospital. Use the elevator button. Talk to Marie. Kiss Marie. Walk southeast, northeast. Use the elevator button. Go to the first floor. Walk to the mens locker room. Take the toilet paper. Use the toiler paper with the toilet. Walk northwest. Talk to the janitor. Walk to the womens locker room. Open Morales’ locker with code 386. Look at the bags. Close the locker. Walk northeast. Use the elevator button. Go to the second floor. Open the eastern door. Talk to captain Tate. Talk to captain Tate. Open the door. Use the elevator button. Go to ground level. Use the car. Drive to the coroner. Open the door. Open the bin Steve Rocklin is in. Look at the toetag. Wait until the coroner returns. Take the envelope. Look at the envelope. Walk southwest. Use the car. Use the elevator button. Look at Marie. Give the locket to Marie. Talk to Marie. Kiss Marie. Walk southeast, northeast. Drive to 500 West Peach. Open the trunk and the case. Take the scraper. Take the bags. Talk to the firefighter chief. Walk inside. Take the photograph. Walk north. Use the scraper with the blood and hair. Walk east, west. Open the trunk and the case. Put the bags in the case. Put the scraper in the case. Close the case and the trunk. Use the car. Leave the car. Go to the army recruiting office. Show the badge to the recruiter. Show the picture of the Bains brothers to the recruiter. Take the printout. Open the door. Use the car. Use the elevator button. Go to the second floor. Walk east. Open the eastern door. Give the military record to the psychologist. Walk south, west. Use the elevator button. Go to ground level. Use the car. Drive to 522 west Palm. Knock on the door. Use the car. Drive to court. Walk northeast. Talk to the judge. Give the photo to the judge. Give the newspaper clipping to the judge. Take the warrant. Walk southwest. Use the car. Drive to 522 west Palm. Knock on the door. Use the car. Drive to court. Walk northeast. Take the warrant. Walk southwest. Use the car. Drive to 522 west Palm. Knock on the door. Draw the gun. Shoot the assailant. Handcuff Michael Bains. Lift the right cushion. Use the remote with the television. Press the 8. Walk in the secret room. Draw the gun. Walk to the table. Walk to the stairs. Shoot the man.
Police Quest 2: The Vengeance
