7. The intention estimating method according to claim 6 , wherein, the calculating the intention co-occurrence weight includes referring to intention hierarchical layer graph data in which said intentions are hierarchized and defined according to the relationship between said intentions to calculate said intention co-occurrence weight by using a weight which is defined for each of said intentions which constructs each hierarchical layer.
7. The intention estimating method according to claim 6 , wherein, the calculating the intention co-occurrence weight includes referring to intention hierarchical layer graph data in which said intentions are hierarchized and defined according to the relationship between said intentions to calculate said intention co-occurrence weight by using a weight which is defined for each of said intentions which constructs each hierarchical layer. 9. The intention estimating method according to claim 7 , wherein said intention hierarchical layer graph data have a relationship in which an intention in a lower hierarchical layer gives a concrete form to an intention in a higher hierarchical layer, and the calculating the intention co-occurrence weight includes referring to said intention hierarchical layer graph data to, when a hierarchical relationship exists between two continuous partial intentions which construct said generated intention sequence, set a preset value as said intention co-occurrence weight, the hierarchical relationship indicating that one or more graph paths exist along a direction from one partial intention of the higher hierarchical layer to another partial intention of the lower hierarchical layer in the intention hierarchical layer graph data.