Since a number of people have asked, my paper with Hana Chockler on responsibility and blame are on my home page (http://www.cs.cornell.edu/home/halpern/papers/blame.pdf (or .../blame.ps). I just posted a new version today (which cleans up some problems with the previous version). I'd be very interested in getting feedback on the paper.
For those who are interested, my papers with Judea Pearl on causality and explanation are also on my home page: http://www.cs.cornell.edu/home/halpern/papers/actcaus.pdf (the causality paper) and http://www.cs.cornell.edu/home/halpern/papers/actcaus1.pdf (the explanation paper). -- Joe
