On the Structure and the Number of Prime Implicants of 2-CNFs
  Let $m(n, k)$ be the maximum number of prime implicants that any $k$-CNF on n variables can have. We show that $3^{n/3} \le m(n,2) \le (1+o(1))3^{n/3}$. 
Navid Talebanfard
cs.DM math.CO