A few months back, I attended a Dagstuhl workshop on Neural-Symbolic Learning and Reasoning – a meeting that tried to bring together people looking at sub-symbolic (primarily but not exclusively neural network) and symbolic (i.e., logic based) learning and reasoning.
I gave a talk on “Learning Action-oriented Symbols: Abstractions over Decision Processes”. This was an attempt at synthesising the idea behind a couple of different papers we have worked for over the past two years.
The report associated with this workshop has now been released: http://drops.dagstuhl.de/opus/volltexte/2015/4884/. It is an interesting collection of ideas, especially if you follow the links to the primary publications and associated background materials.