samzenpus from the follow-the-money dept.
An anonymous reader writes "After a recent Slashdot story detailing the errant investigation into a credit card holder's dept payment, comes this article from the Christian Science Monitor discussing the commoditization of terrorism, its relationship to crime, and the difficulties encountered when trying to track "bad" money."
We warn the reader in advance that the proof presented here depends on a
clever but highly unmotivated trick.
-- Howard Anton, "Elementary Linear Algebra"