1. A method of searching a lattice for problem-solving in artificial intelligence using a data processor, the lattice including nodes having present and next nodes each having node scores, and the lattice having depth and breadth, said method comprising the steps of: (a) inputting pattern data sets using an input device and storing the pattern data sets in a memory; (b) determining candidate patterns for each of the input pattern data sets; (c) generating pattern scores for the candidate patterns based on a similarity between the pattern data sets and the candidate patterns using the data processor to determine which candidate patterns are assigned to the nodes of the lattice so that the candidate patterns for each of the pattern data sets are arranged at a specific depth of the lattice in order of the breadth of the lattice according to the respective pattern scores thereof; (d) calculating differences between the node scores of the nodes with the same depth using the data processor; (e) calculating a search priority index for each of the nodes corresponding to the candidate patterns having a search priority based on the differences of the node scores of the nodes with the same depth using the data processor; and (f) searching the lattice according to the search priority indexes and finding patterns corresponding to the pattern data sets using the data processor.