LAX uses random numbers theory to place security check points

Here is something unexpected: Security officials at Los Angeles International Airport have decided to equip themselves with a new weapon in their fight against terrorism: Complete, and rather baffling, randomness (some visitors to LAX would swear that this method has been in use at the airport for quite some time now). Eager to thwart future terror attacks in the early stages while plotters are casing the airport, LAX security patrols have begun using a new software program called ARMOR to make the placement of security checkpoints completely unpredictable. All airport security officials have to do is press a button labeled “Randomize,” and they can throw a sort of digital cloak of invisibility over where they place the cops’ antiterror checkpoints on any given day. MSNBC reports that the application was developed by computer scientists at the University of Southern California and believed to be the first program of its kind to be used at an airport. ARMOR aims to thwart terror plots during the early, surveillance phase, when would-be attackers typically begin watching their target “18 months to four years prior to an attack” to look for security weaknesses, says James Butts, deputy executive director of law enforcement at Los Angeles World Airports, which runs LAX and other city-owned airports. “Part of it is to look for patterns in the deployment of assets. We’re trying to block the surveillance cycle” by making the security patrols appear in unpredictable places at unpredictable times.

Randomness is not easy. Even when they want to be unpredictable, people follow patterns. “Unconsciously, (security forces) develop predictable patrol behaviors,” as Butts says. This is why the new software helps, and the folks at LAX turned to the computer scientists at USC’s Viterbi School of Engineering. The ARMOR software is the real-world product of an idea which began as an academic question in game theory. USC doctoral student Praveen Paruchuri sought to find a way for one “agent” (or robot or company) to react to an adversary who has perfect information about the agent’s decisions. Using artificial intelligence and game theory, Paruchuri wrote a new, fast set of algorithms to randomize the actions of the first agent. When he took the paper to prestigious AI conferences, however, nobody would publish the work. The basic reaction: Great math, but so what? “They said, ‘We don’t see a practical use for it’,” says Milind Tambe, the USC engineering professor who led the ARMOR team. “It was very disappointing.” LAX officials saw things differently. Under a mandate from L.A. Mayor Antonio Villaraigosa to improve airport security, they were on the lookout for new ideas. So when a former FBI agent named Erroll Southers, who works at a USC security program funded by DHS, told LAX officials about it, they agreed to meet with the USC team in April. Over the summer grad students fed vast amounts of classified data about the airport’s facilities into the program, and ARMOR started running in August, according to Butts.

The nation’s fifth-biggest airport is “one of the top targets on the West Coast,” says Butts. The “millennium plot” of 31 December 1999, aimed to set off explosives at LAX. Federal agents broke up the plot when they arrested Algerian Ahmed Ressam entering the U.S. from Canada with a car laden with explosives. He was later convicted on terrorism charges. On 4 July 2002, an Egyptian immigrant named Hesham Hadayet opened fire at the El Al counter at LAX, killing two and wounding four. Airport officials have at least one new task for the software. Soon ARMOR will begin jumbling the placement of the bomb-sniffing canine patrols too, says Butts. Other potential uses are too secret to talk about. Butts says that the new random placement “makes travelers safer” and even gives them “a greater feeling of police presence” by making the cops appear more numerous. That’s good for visitors, and, officials hope, bad for would-be terrorists.