What probability is about

Just as formal logic is a tool for capturing intuitions about effective ways of reasoning probability is a tool for capturing effective ways of reasoning about uncertainty.  In logic, we are taught to proceed from premises to conclusions. We conclude  that "If every CSE graduate takes the exit exam  before graduating and Emily is a CSE graduate, then Emily must have taken the exam" because this matches the Modus ponens pattern .  The good thing about this is that if we trust Modus ponens and we believe that we have correctly mapped the English description of the conclusion onto the terms of the formula, we know that the argument is valid. Notice that this claim of validity is not affected by the truth or falsity of the premises. Even if Emily never was a CSE student, or even if some CSE students are in fact able to weasel out of taking the exit exam, the argument is still OK. Not, however, especially useful as a way of working out stuff about Emily: if we aren't sure about the assumptions, we can't be sure about the conclusion either. Aristotle hit on the idea of laying out a taxonomy of plausible ways of reasoning, then thinking, in the abstract, about which of these patterns of reasoning actually deliver valid arguments. This is a wonderful idea, because you can rely on the insights about the patterns of reasoning without having to be concerned about the truth or falsity of particular facts.

In the same way that logic is the study of patterns of true/false reasoning, probability is the study of patterns of reasoning in the face of uncertainty.

Teaching in Tübingen

I just spent a very happy couple of weeks teaching a compact (=insanely intensive) course from Croft, Metzler, Strohman's Search Engines: Information Retrieval in Practice. Really good textbook. Teaching four hours a day for two weeks is actually feasible! There were some nice projects: two groups added Named Entity tagging and one made a Russian version of Galago.

The Black Chamber Society

For the past few years I have been running a Codes and Code Breaking course at Ohio State. We got the idea from Chris Kennedy who taught a similar course at Northwestern, and before that at UCSD, where the course has now been pushed in a slightly different direction by Andy Kehler. It's a very enjoyable course to teach.The way we do it there is a lot of problem solving and group work, and just a smidge of modern stuff like public key cryptography. We feed the people who become passionate about the math and CS aspects into courses like Steve Lai's graduate CSE class. I am grateful to the National Science Foundation for helping support the course in its early years. Most of the students come from Linguistics or from the Security and Intelligence major. They're delightful (usually) and smart (on average). Both Linguistics and International Studies seem to get many students who enjoy learning and are good at it.

We are beginning to open this course up to be taught by graduate students as well as faculty. The first graduate instructor is the wonderful DJ Hovermale who uses new-fangled avian social media to give clues to the assignments. He also sometimes uses disguise, confederates and a thick Russian accent to make the first lecture into a coup de theatre. When I teach the class again, I'll need to up my game.

The students last quarter were so fired up by all this that they decided to keep the thing going as a student society. So we have (drumroll) The Black Chamber Society. This is immensely gratifying.  Thanks to all concerned.