An information processing apparatus according to the present invention comprises a generation section configured to generate an ordered tree structure by defining transition edges between nodes using, as transition conditions, respective constraints from one or more constraint pattern each including plural constraints, a search section configured to search for a second substructure K similar to a first substructure P from a root node by determining a set relation between transition conditions of respective transition edges, and a transition defining section configured to define an additional transition link from a tail node sKn of the second substructure K to a child node sPn+1 of the first substructure P, the additional transition link adding a constraint to be met by an indeterminant identified from the set relation, wherein a data structure for pattern matching is defined.