* Dan Hinkel takes a look at the latest data on where Chicago's guns come from; it lines up with data from previous years:

The research shows that some 29 percent of the guns recovered on Chicago’s streets between 2008 and the end of March were bought in the Cook County suburbs. Lake County, Ind., was the second largest source, accounting for six percent of the weapons, and other counties surrounding Chicago – including Lake County, Ill., and Will, DuPage and Kane counties – were also in the top 10 sources.

[snip]

Ander said she was surprised by the percentage of guns that came from Illinois, rather than from neighboring states with comparatively relaxed gun laws. About 42 percent of the guns came from Illinois.

Perhaps surprising, but as I wrote awhile back, it's easy enough to get a gun in Illinois that convenience of location appears to be the most important factor (it's easier to buy guns in other states, but it adds complications to trafficking them). What was surprising to me was the percentage of guns that come all the way from Mississippi, likely a matter of social connections.

* How's it so easy to get guns? A good piece by Frank Main delves into the method David Bernstein found in his "Biography of a Gun" piece: straw purchasers.

Straw purchasers like Spencer have clean records that allow them to get an Illinois firearm owner’s identification card. With a FOID card, they can purchase guns for people banned from owning them. They sign a federal form saying they’re the “actual” buyer when they really aren’t.

That's all it takes. It's practically the same loophole gangsters used to get guns back in the 1930s.

Main also looks at why so many of our guns—not a high percentage in general, but high given its distance—come from Mississippi: "In Mississippi, gun owners are not required to go through a state background check to obtain a permit, as they are in Illinois. They only have to present a valid driver’s license or state ID to a gun store, which still must perform a federally required background check."

It's hard to bust both straw purchasers and dealers who sell to straw purchasers, even ones who are blatantly selling to straw purchasers, a dilemma at the heart of the Fast and Furious fiasco.

* If you followed the news of Thursday's rash of shootings, you might recall that the cops were having trouble getting the victims to talk. It's a problem: "Chicago police have suspended nearly 80 percent of their investigations into nonfatal shootings on the grounds that victims wouldn't cooperate."

If that sounds insane, try thinking about it in the abstract (emphasis mine):

The Prisoner’s Dilemma itself is well established as a way to study the emergence of cooperative behavior. Each player is simultaneously offered two options: to cooperate or defect. If both players cooperate, they each receive the same payoff, R; if both defect, they each receive a lower payoff, P. However, if one player cooperates and the other defects, the defector receives the largest possible payoff, T, and the cooperator the lowest possible payoff, S.

If the Prisoner’s Dilemma is played only once, it always pays to defect—even though both players would benefit by both cooperating. Thus, the game seems to offer a grim, and unfamiliar, view of social interactions. If the game is played more than once, however, other strategies, that reward cooperation and punish defection, can dominate the defectors, especially when played in a spatial context or for an indeterminate number of rounds (6–8). Thus, the Iterated Prisoner’s Dilemma (IPD) offers a more hopeful, and more recognizable, view of human behavior.

"Hopeful and recognizable," depending on your perspective. If you keep playing prisoner's dilemma in a world where everyone knows how the game is played, it's possible to come to a depressing plateau:

[K]nowledge of ZD [zero determinant] strategies offers sentient players an even better option: both can agree to unilaterally set the other’s score to an agreed value (presumably the maximum possible). Neither player can then improve his or her score by violating this treaty, and each is punished for any purely malicious violation.

If you want to keep playing the game, it's better to cooperate, a strategy hardly unique to gangland or any other institutionally dominated culture.

* Natalie Moore looks into how we categorize gang crime, and what that means: gang-related vs. gang-motivated vs. gang-associated crimes.

Photograph: Chicago Tribune