Editor's Notes for October 2009

I've done a great deal of writing lately but, much to my chagrin, none of it has been here. There is good reason for the digression (proposals, submissions), but I am troubled by the appearance of neglect or lifelessness in this corner, and so, to avoid this, a few passing points of interest and some encouraging news:

1. Return-Oriented Programming: a colleague recently pointed out to me an extremely interesting finding reported at last year's Black Hat USA Briefings. The authors present a exploit that allows them to perform arbitrary computation without injecting code. If an attacker can gain control the stack, the authors show, he can influence program control flow to link together certain segments of code into instruction sequences of his choosing. This is very neat because it is one of those things that seems as if it should possible in principle. However, we so often hear in computer science about humanly impractical things that are "possible in principle"; here is someone who has taken the principle and successfully used it. Well done!



2. Iterated Function Systems and Control Languages: I was very pleasantly astonished when, in the course of combing the literature aimlessly, I discovered the recent work of Henning Fernau and Ludwig Staiger, which appears to be a link between automata theory and fractal geometry. Intuitively (and offering no justification other than that), I feel as if such correspondence makes sense, and I admit to being thrilled that skilled mathematicians have undertaken to actually investigate such a correspondence. This also suggests the surprising possibility that abstract computer science might eventually have substantive theoretical contributions outside of its own domain. Well done!



3. Why doesn't Wendell Berry own a computer, and why don't I own a mule?



4. The Liar Paradox Redux: It occurred to me yesterday that the situation I constructed in the Truth Machine thought experiment was actually an elaborate variant of the famous Twin Paradox. The paradox is not really a paradox so much a puzzle, stated as follows: you meet a pair of identical twins, one of whom always tells the truth, and one of whom always lies. What single question can you ask them to determine which is which? (I would also note that this familiar paradox appears to be a favorite intellectual toy of accomplished animator Genndy Tartakovsky, as the puzzle and its solution has appeared in episodes of both The Powerpuff Girls and Samurai Jack.) That's not to say that there isn't a great deal more to the Truth Machine example than there is to this familiar puzzle, only that I hadn't realized the connection before. Interestingly, it appears that I unwittingly attempted to construct something like the solution to the Twin Paradox as one stage in the elaboration of the Truth Machine.



5. A Second Editor's Note on the Truth Machine: Another thing I had not realized until recently is that The Truth Machine is also the title of a novel by science fiction writer James Halperin. It appears that Mr. Halperin's truth machine is not quite so general in its function, acting in the restricted (but still remarkable) role of an infallible human lie detector, with horrible dystopian consequences. Why is it always the case that catching falsehoods leads to so many unforeseen complications? This seems like a question worth answering.



6. What happens to the story of Job if you reverse the "good" and "evil" roles, i.e. make Job an extremely wicked man who only persists in evil because it's so materially rewarding?



7. Is there such a fallacy as "appeal to chaos"?

I'm afraid that's all the time we have for now. Until next time!