Patent ID: 7844598

Claim:
A question answering system having a processor, comprising: a question dividing unit that applies a predetermined question dividing rule to an input question, to divide the input question into sub-questions; a question answering unit that acquires a plurality of answer candidates corresponding to each sub-question generated by the question dividing unit, and acquires certainty values of each answer candidate corresponding to each sub-question generated by the question dividing unit, the certainty values of the answer candidates serving as reliability indexes; and an answer determination unit that identifies common answer candidates provided by the question answering unit, calculates a sum of the certainly values corresponding to each common answer candidate, and selects one answer candidate having the largest sum of the certainty values from among the plurality of answer candidates acquired for the sub-questions, as an answer to the input question, wherein the processor controls the question dividing unit, the question answering unit, and the answer determination unit, and the question dividing unit references the answer candidates acquired by the question answering unit, and further divides the input question if no answer candidate having a certainty value exceeding a given threshold value is found.