it seems pretty obvious that knowledge of AIXI is the most important part of the mathematical background for work in Friendly AI.
Possibly. That was my initial reaction as well, but now I'm not so sure.
epistemology seems too important to leave to non-mathematical methods.
Agreed.
I searched the posts but didn't find a great deal of relevant information. Has anyone taken a serious crack at it, preferably someone who would like to share their thoughts? Is the material worthwhile? Are there any dubious portions or any sections one might want to avoid reading (either due to bad ideas or for time saving reasons)? I'm considering investing a chunk of time into investigating Legg's work so any feedback would be much appreciated, and it seems likely that there might be others who would like some perspective on it as well.