3. The computer implemented prosodic control rule generation method according to claim 1 , wherein the estimating estimates the punctuation mark incidence at the boundary between a “j−1” (j is a positive integer)- and “j”-th language units from the beginning of the input text, based on each of “I+1” language unit sequences each including I language units starting with a “j−i” (i=0, 1, . . . , I, I is a positive integer equal to or larger than 1)-th language unit.
3. The computer implemented prosodic control rule generation method according to claim 1 , wherein the estimating estimates the punctuation mark incidence at the boundary between a “j−1” (j is a positive integer)- and “j”-th language units from the beginning of the input text, based on each of “I+1” language unit sequences each including I language units starting with a “j−i” (i=0, 1, . . . , I, I is a positive integer equal to or larger than 1)-th language unit. 4. The computer implemented prosodic control rule generation method according to claim 3 , wherein the punctuation mark incidence at the boundary between the “j−1”-th language unit and the “j”-th language unit is a weighted average of “I+1” punctuation mark incidences at the boundary between the “j−1”-th language unit and the “j”-th language unit, the “I+1” punctuation mark incidences each being estimated from an arrangement of word classes in respective “I+1” language unit sequences.