# HG changeset patch
# User zhang
# Date 1314973794 0
# Node ID 6bb8ad9093e67011537363dcdbaf448b7af93ec1
# Parent  2087fc59f2a1a71c2bda74288a5456084452584b
More modification by Xingyuan.

diff -r 2087fc59f2a1 -r 6bb8ad9093e6 csupp.pdf
Binary file csupp.pdf has changed
diff -r 2087fc59f2a1 -r 6bb8ad9093e6 csupp.tex
--- a/csupp.tex	Fri Sep 02 14:11:36 2011 +0000
+++ b/csupp.tex	Fri Sep 02 14:29:54 2011 +0000
@@ -68,7 +68,11 @@
 
 \section*{Proposed Work}
 
-One new development in formal grammar is the Parsing Expression Grammar (PEG) which is proposed as an refinement of standard Context Free Grammar. The idea is to introduce negative, conjunctive operators as well as production priorities, so that ambiguity abound in CFG can be eliminated. Another benefit of PEG is that it admits a very efficient linear parsing algorithm.
+One new development in formal grammar is the Parsing Expression Grammar (PEG) which is proposed as an refinement of standard Context Free Grammar. The aim of this extension is to internalize disambiguition normally done with semantic methods. 
+The idea is to introduce negative, conjunctive operators as well as production priorities, so that the grammars written in
+PEG are unambiguous in the first place. Another benefit of PEG is that it admits a very efficient linear parsing algorithm.
+
+However, one disadvantage of PEG is that it does not allow left recursion in grammar specification, i.e., standard parsing algorithms of PEG can not deal with left recursion. Although some authors claimed PEG parsing algorithms for left recursion, none of them provide correctness proof, not even in paper-and-pencil form. 
 
 
 \mbox{}\\[15cm]