Way beyond my limited understanding. What I glean from it, is that, under certain conditions, monetary policy needs to encourage inflation or risk a Japan style meltdown.
Very long [link|http://web.mit.edu/krugman/www/trioshrt.html|paper] by Paul Krugman from 12/99. Lots of formulas and equations that I don't even begin to understand. His english language explanations are just barely comprehensible (to me).
A google search on [link|http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=%22liquidity+trap%22|liquidity trap] gets a large number of hits.