An Intuitive Procedure for Converting PDA to CFG, by Construction of   Single State PDA
  We present here the proof for an alternative procedure to convert a Push Down Automata (PDA) into a Context Free Grammar (CFG). The procedure involves intermediate conversion to a single state PDA. In view of the authors, this conversion is conceptually intuitive and can serve as a teaching aid for the relevant topics. 
Arjun Bhardwaj and N.S. Narayanaswamy
cs.FL