I rises this question because I read Tim's question "Why are Hornsat, 3sat and 2sat not equivalent?"
"... This new problem though is polynomial time equivalent to a certain instance of 2SAT(satisfiable iff the HORNSAT is). ..."
How can I build the "certain instance of 2SAT"?
May anybody give me pointers to papers that help writing the polynomial reduction from HORNSAT to 2SAT?