1. A computer readable medium storing instructions which, when executed by a computer, cause the computer to perform a method of determining a relationship between first and second textual inputs, the method comprising: analyzing the first textual input to obtain relations of constituents thereof; determining a relative importance of the constituents in determining the relationship between the first and second textual inputs based on the relations obtained; and determining the relationship between the first and second textual inputs based on the constituents and the relative importance of the constituents.