The frames in my previous post could be implemented in a graph database, or RDF triples. It's similar to the representation used in Cyc.

I'm quite happy with a hybrid symbolic/statistical approach, which could be useful for disambiguating words and phrases in context.

I think the trick is to avoid generating the parse tree in the first place.

Today's hardware is pessimized for symbol and list processing. They can't be done on GPUs, and CPUs work better on contiguous data.