1. An information processing apparatus comprising: at least one central processing unit (CPU) configured to: create a network in which respective characters of a plurality of character recognition results are represented as nodes, and in which nodes of adjacent character images are connected with a link; determine a first candidate boundary in the network; determine a second candidate boundary different from the first candidate boundary in the network; and extract, as to-be-searched objects, a plurality of candidate character strings from a set of candidate character strings each formed of nodes between the first candidate boundary and the second candidate boundary, wherein the at least one central processing unit (CPU) determines, as the second candidate boundary, a position located a predetermined number of nodes away from the first candidate boundary.