Earley-based structural transfer for Apertium

Perhaps [Earley's algorithm http://en.wikipedia.org/wiki/Earley's_algorithm] to parse context-free grammars (which has a left-to-right longest-match philosophy as Apertium) could be used to perform more complex syntactical transformations; this could be useful for distant language pairs containing embedded structures.

Open questions:

• Currently, Apertium uses text streams to communicate. I assume this would not be possible here.
• When would one call the bilingual dictionary? Apertium Level 2 calls it in the first stage.
• We should check whether this has been done before.

Further reading

• http://www.isi.edu/natural-language/mt/hlt-naacl-06-zhang.pdf
• http://www.slt.atr.jp/IWSLT2006/proceedings/EC_13_NTT.pdf
• http://acl.ldc.upenn.edu/P/P96/P96-1020.pdf
• http://www.iai.uni-sb.de/docs/meta93.pdf