2. The method according to claim 1, wherein the step of assigning further comprises: a routine step of sequentially repeating said grammar rule analysis step and said reference category reapplication step until the grammar rule analysis succeeds at least once by applying at least one reference syntactic category selected from among said reference syntactic categories applied to said undefined word.
2. The method according to claim 1, wherein the step of assigning further comprises: a routine step of sequentially repeating said grammar rule analysis step and said reference category reapplication step until the grammar rule analysis succeeds at least once by applying at least one reference syntactic category selected from among said reference syntactic categories applied to said undefined word. 4. The method according to claim 2, wherein said retrieving step comprises the steps of: decomposing said input sentence into said plurality of input words; consulting said dictionary section for each of said input words, to detect the defined word corresponding to each input word on a one-to-one basis; and determining, as the syntactic category of each said input words, the syntactic category belonging to each detected defined word.