Ōno's lexical law

The law was discovered by Japanese linguist Susumu Ōno and published in 1956.

[1] The law states that, for the nine literary works under consideration (one work is in two editions, hence ten manuscripts total), the percentage of words in each of the four given word classes vary simultaneously linearly, between the most noun-heavy Man'yōshū and the most verb-heavy Tale of Genji.

The horizontal axis (in Ōno's formulation) is arbitrary, and should not be interpreted as time.

The graph in the re-formulation by Mizutani is more easily interpreted, and shows a scatter plot of nouns versus other word classes.

Connecting the two points for the noun reveals a monotonically decreasing line, while connecting the two points for any of the other word classes results in a monotonically increasing line.

Plot an additional point corresponding to any of the other seven classic works on each line of the word classes.

[1] Let the rates of noun usage in the lexicon of 3 arbitrary literary works A, B, and C be

Fig.1 Rates of word classes in Japanese classical literary works. [ 2 ]
Fig. 2. Plot of (x i ,y i ) of a literary work i based on the revised law by Mizutani. x i denotes the rate of noun and y i , the rate of a word class. For each word class, a least squares line is depicted.