The investment bank Goldman Sachs is being sued by the SEC for allegedly selling an investment designed to lose money. The investment was built on a pool of mortgages that were likely to go into default. Initially, Erik Gerding at The Conglomerate (a legal blog) thought that the SEC would have difficulty winning the case, since Goldman had disclosed the contents of the pool. Then he had second thoughts, because of this paper, “Computational Complexity and Information Asymmetry in Financial Products”, by Arora, Barak, Brunnermeier, and Ge. The paper shows that even if you know the contents of the pool, detecting whether bad mortgages are hidden in the pool is an NP-complete problem, which is normally considered the hallmark of computational intractability.

In some disciplines, there is the notion of a Comment on a published article, which is what it sounds like: a short comment about the contents of the article (for example, that it’s wrong). Cat Dynamics links to an interesting account of physicist Rick Trebino’s (lengthy but ultimately successful) attempts to publish a Comment explaining why a published article is wrong.

I don’t think I’ve ever seen a Comment in a pure math journal. They’re common in statistics journals.

The New York Times has an online math blog by Steven Strogatz. Given the venue, it is written for an elementary audience. Here is a recent post on the method of exhaustion and how it allows you to approximate π.

The Insane Clown Posse has declared war on scientists. Check out these recent lyrics (warning, curse words ahead):

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When I said that I was about to eat a big bowl of non-blogging, I didn’t mean that I was going to turn off the website, but apparently that’s what the server thought I meant. I didn’t realize initially that the site was down because I was having unrelated DNS issues, and I thought that’s why I couldn’t access the site.

I discovered that the site was back up when I received my first notification that somebody had posted spam in the comment section.