First, CCG is not a parser --- the Grok system has the implementation of a parser that uses CCG as its underlying grammatical framework.
If your question is what are the advantages of CCG over other formalisms, that is a question with a very long answer. For starters, see my dissertation, which is available at:
A lot of the argumentation there is linguistic, but there is also some discussion of the use of CCG in parsing systems, and references to other work on CCG parsing.
PCFG's are a probablistic extention of context-free grammars. For information on probabilistic CCG, see work by Julia Hockenmaier:
Welcome to Categorial grammar
where can i get a formal introduction to CCG formalism and examples for the same
A good place to start is Mark Steedman's publications page:
http://www.cogsci.ed.ac.uk/~steedman/papers.html
In particular, see:
ftp://ftp.cis.upenn.edu/pub/steedman/ccg/ccgintro.ps.gz
If you can get a copy of the book "The Syntactic Process", that is probably the best starting point.
Also, for links to info on other kinds of categorial grammar:
http://www.cs.man.ac.uk/ai/CG/
Hope that helps!
What's the difference (advantages) between CCG and other parsers such as PCFG?
First, CCG is not a parser --- the Grok system has the implementation of a parser that uses CCG as its underlying grammatical framework.
If your question is what are the advantages of CCG over other formalisms, that is a question with a very long answer. For starters, see my dissertation, which is available at:
http://www.iccs.informatics.ed.ac.uk/~jmb/dissertation/index.html
A lot of the argumentation there is linguistic, but there is also some discussion of the use of CCG in parsing systems, and references to other work on CCG parsing.
PCFG's are a probablistic extention of context-free grammars. For information on probabilistic CCG, see work by Julia Hockenmaier:
http://www.cogsci.ed.ac.uk/~julia/
Hope that helps!
Jason