A general computation rule for lossy summaries/messages with examples   from equalization
  Elaborating on prior work by Minka, we formulate a general computation rule for lossy messages. An important special case (with many applications in communications) is the conversion of "soft-bit" messages to Gaussian messages. By this method, the performance of a Kalman equalizer is improved, both for uncoded and coded transmission. 
Junli Hu, Hans-Andrea Loeliger, Justin Dauwels, and Frank Kschischang