“…In the last two decades, many papers have appeared in the literature on the existence of solutions of E P ( f ); see, for example (Blum and Oettli 1994; Combettes and Hirstoaga 2005) and references therein. Some solution methods have been proposed to solve the E P ( f ); see, for example, (Blum and Oettli 1994; Combettes and Hirstoaga 2005; Jaiboon and Kumam 2010; Katchang and Kumam 2010; Kumam 2009; Moudafi 2003; Qin et al 2009a, 2009b, 2009c; Saewan and Kumam 2010b, 2011a, 2011b, 2011c, 2011d, 2011e, 2011f, 2011g, 2012b; Zegeye et al 2010) and references therein.…”