A more subtle example is weighted FSAs that approximate PCFGs ( Nederhof , 2000 ; Mohri and Nederhof , 2001 ) , or to extend the idea , weighted FSTs that approximate joint or conditional synchronous PCFGs built for translation .
practical experiments with regular approximation of contextfree languages
Mark-Jan Nederhof
Arbitrary weights such as 2.7 may be assigned to arcs or sprinkled through a regexp ( to be compiled into E : E/2 .7 â ) arcs ) . A more subtle example is weighted FSAs that approximate PCFGs ( Nederhof , 2000 ; Mohri and Nederhof , 2001 ) , or to extend the idea , weighted FSTs that approximate joint or conditional synchronous PCFGs built for translation . These are parameterized by the PCFG 's parameters , but add or remove strings of the PCFG to leave an improper probability distribution .
A more subtle example is weighted FSAs that approximate PCFGs ( @@CITATION ; Mohri and Nederhof , 2001 ) , or to extend the idea , weighted FSTs that approximate joint or conditional synchronous PCFGs built for translation .