Journal of Quantitative Linguistics
2004, Vol. 11, No. 3, pp. 233–250
DOI: 10.1080/0929617042000314976

Entropy and Redundancy of Japanese Lexicaland Syntactic Compound Verbs
Katsuo Tamaoka1, Hyunjung Lim, and Sakai Hiromu
Hiroshima University, Japan

ABSTRACTThe present study investigated Japanese lexical and syntactic compound verbs (V1 þ V2) using
Shannon’s concept of entropy and redundancy calculated using corpora from the Mainichi
Newspaper and a collection of selected novels. Comparing combinations of a V2 verb withvarious V1 verbs, syntactic compounds were higher in entropy than lexical ones while neither
differed in redundancy. This result suggests that V2 verbs of syntactic compounds are likely to
combine with a wider range of V1 verbs than those of lexical compounds. Two exceptional V2
verbs, komu and ageru, both of which create lexical compounds, showed a wide variety of
combinations with V1 and therefore act like prefixes in English. Comparing V2 verbs in the two
corpora, the V2 eru, which adds the meaning of ‘‘possibility’’ to a V1, functions like the auxiliaryverb ‘‘can’’ in English and seems to be a favored expression in newspapers. In contrast, the V2
komu, adds the meaning of ‘‘internal movement’’ similar to the preposition ‘‘into’’ in English andappears to be preferred in the novels to enrich the expression of lexical compounds. In general,
both lexical and syntactic compounds were used similarly in both corpora.

1. INTRODUCTION
The Japanese language frequently combines two verbs to make compoundverbs. These compounds are further classified into two groups, lexical andsyntactic compounds (Kageyama, 1993, 1999a, 1999b). Lexical compoundverbs are mostly limited to lexically-specified combinations of the firstlypositioned verbs (V1) and the secondly-positioned verbs (V2) to constructconventional meanings such as tabe þ kuraberu (eat þ compare),nomi þ aruku (drink þ walk) and kaki þ toru (write þ take). For the syntactic1
Address correspondence to: Katsuo Tamaoka, International Student Center, Hiroshima
University, 1-1, 1-chome, Kagamiyama, Higashi-Hiroshima, 739-8524 Japan. Tel.: 0824-246288. Fax: 0824-24-6288. E-mail: ktamaoka@hiroshima-u.ac.jp0929-6174/04/1103-233$16.00 # Taylor & Francis Ltd.

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K. TAMAOKA ET AL.

Fig. 1. Syntactic structure of lexical and syntactic compound verbs.
Note: NP-o refers to an accusative case-marked noun phrase.

structure of lexical compound verbs such as those shown in Figure 1, twoverbs of V1 nomi (drink) and V2 kuraberu (compare) construct a single
compound verb nomikuraberu, and further construct a verb phrase with anaccusative noun phrase koohee-o (coffee). In contrast, syntactic compoundverbs generally do not have idiosyncratic lexical combinations of two verbs,
so that they are rather semantically transparent, such as tabe þ hazimeru(eat þ begin), nomi þ oeru (drink þ finish) and kaki þ naosu (write þ fix).
For the syntactic compound verbs, the accusative noun phrase koohee-o andV1 nomi construct the first verb phrase VP1, and are further combined with
the V2 oeru (finish) to produce the second verb phrase VP2. These
differences in syntactic structure predict frequencies of appearance; certain

JAPANESE LEXICAL AND SYNTACTIC COMPOUND VERBS

235

verb combinations are seen with a high frequency for lexical compoundverbs, whereas a variety of combinations based upon V2 are seen for
syntactic compound verbs. The present study counted token and type
frequencies of compound verbs based on V2, using two different corpora, theMainichi Newspaper and the older novel collection of Aozora Bunko.
Furthermore, using these frequency figures, mathematical indexes of‘‘entropy’’ and ‘‘redundancy’’ were calculated in order to clarify thedifferences between lexical and syntactic compound verbs.
2. ENTROPY AND REDUNDANCYThe concepts of entropy and redundancy were first developed by an Americanmathematician, Claude Elwood Shannon (1916–2001), in his well-known
work, A Mathematical Theory of Communication (1948). Since these concepts
can be applied to a wider range of corpus size, characteristics of lexical andsyntactic compound verbs are directly compared in appearance in both
corpora of the Mainichi Newspaper and Aozora Bunko.
Entropy is an index for the degree of disorder or chaos (for details, see
Hori, 1979; Kaiho, 1989). For compound verbs, entropy refers to how randomly V2 is combined to various V1, and it is calculated using the following
formula:jX
pj log2 pj
H¼
j¼1

In the present study, the entropy of compound verbs was calculated on thebasis of the second verb V2. For example, V2 aruku (walk), which produces
lexical compound verbs, appeared to be combined with 18 different verbs inthe newspaper corpus. The total of V2 appearance with other verbs was 44,
with uri þ aruku (a combination of sell and walk) having the highest
frequency at 7, and tazune þ aruku (a combination of visit and walk) was thesecond highest at 6. The p in the formula stands for the probability of
appearance for a specific compound verb among all the compounds createdwith V2. In the case of V2 aruku, p is 0.159, as calculated by dividing 7 by 44.
The formula log2Pj for aruku is simply counted as log2 0.159 ¼ 2.652. Then,pj log2 pj for the V2 aruku is 0.422 (the result of 0.159 2.652). In the samemanner, the values for the remaining 17 compound verbs were also calculated.

236

K. TAMAOKA ET AL.

The entropy of the V2 aruku is finally determined as 3.780 by adding all thesescores and dividing by 1. The calculation for aruku is as follows:H ¼ ð7=44Þlog2 ð7=44Þ  ð6=44Þlog2 ð6=44Þ  ð5=44Þlog2 ð5=44Þ ð5=44Þlog2 ð5=44Þ  ð3=44Þlog2 ð3=44Þ  ð3=44Þlog2 ð3=44Þ ð2=44Þlog2 ð2=44Þ  ð2=44Þlog2 ð2=44Þ  ð2=44Þlog2 ð2=44Þ ð1=44Þlog2 ð1=44Þ  ð1=44Þlog2 ð1=44Þ  ð1=44Þlog2 ð1=44Þ ð1=44Þlog2 ð1=44Þ  ð1=44Þlog2 ð1=44Þ  ð1=44Þlog2 ð1=44Þ ð1=44Þlog2 ð1=44Þ  ð1=44Þlog2 ð1=44Þ  ð1=44Þlog2 ð1=44Þ ¼ 3:780
In addition to entropy, another well-known mathematical concept by
Shannon is redundancy, which refers to the degree of superfluousness. For
compound verbs, it implies frequency bias in appearance, indicating, forinstance, repeatedly used expressions in the same corpus. Redundancy isdetermined using the following formula.
R ¼ ð1  H=Hmax Þ  100ð%Þ
H refers to entropy, whereas Hmax indicates maximum entropy. Maximum
entropy for compound verbs implies that any verb would be combined with V2
in the same probability, as produced by the following formula.
Hmax ¼ log2 J
As with the aforementioned example of aruku, Hmax is calculated to be 4.170
using logarithm log2 of type frequency J. This figure shows the entropy for 18
different verbs (V1) equally (i.e., the same token frequency) when combinedwith V2 aruku. Redundancy for aruku is now calculated as a percentage: theresult of the figure for entropy (3.780) multiplied by the maximum entropy(4.170) is subtracted from 1.
At a glance, redundancy seems to have a negative correlation of 1 withentropy, but the entropy and redundancy for V2 correlated moderately as0.5489 for the newspaper corpus (n ¼ 48) and 0.217 for the novel corpus(n ¼ 37). Therefore, these two concepts can be treated as different
measurements. An advantage of entropy and redundancy is that they can beused with different sizes of relatively large corpora (excluding smaller sizes),
so the present study utilized these concepts to compare characteristics oflexical and syntactic compound verbs in both the ‘‘newspaper and novels’’corpora. As shown in Figure 1, V2 of syntactic compound verbs is freely

JAPANESE LEXICAL AND SYNTACTIC COMPOUND VERBS

237

combined with VP1 whereas V2 of lexical compound verbs appears as a part ofa V1 þ V2 single verb. Therefore, it is hypothesized that syntactic compoundverbs would be more likely to be higher in entropy and lower in redundancy
than lexical compound verbs.

3. FREQUENCY, ENTROPY AND REDUNDANCYOF COMPOUND VERBS FROM THE MAINICHI NEWSPAPER
The present study used editions of the Mainichi Newspaper published from 1991
to 1994, consisting of a total token frequency of 88,454,573 words. A total of
48 V2 verbs were selected from the pool of 88 lexical compound and 21 syntactic compound verbs (108 V2 candidates), using more than 10 token frequencies
out of 88,454,573 words appearing in the Maichini Newspaper as a baseline.
3.1. Comparison of Lexical and Syntactic Compound Verbs
One-way analyses of variance (ANOVAs) were conducted with lexical andsyntactic compound verbs. The ANOVA for entropy indicated that lexicalcompound verbs (n ¼ 37, M ¼ 2.97, SD ¼ 1.16) were significantly lower thansyntactic compound verbs (n ¼ 11, M ¼ 4.38, SD ¼ 1.95) [F(1, 46) ¼ 8.95,
p < .01]. In contrast, the ANOVA for redundancy indicated no significant
difference between lexical compound verbs (n ¼ 37, M ¼ 18.43, SD ¼ 15.72)
and syntactic compound verbs (n ¼ 11, M ¼ 24.96, SD ¼ 25.88)[F(1, 46) ¼ 0.31, n.s.]. These results suggest that V2 verbs of syntactic
compounds combined irregularly with various V1 verbs in comparison to theV2 verbs of the lexical compounds. As depicted in Figure 1, the two verbs ofV1 and V2 for the lexical compounds strongly combine as lexicallyidiosyncratic, seeming to appear as V1 þ V2 on a regular basis. In contrast,
since V2 verbs of syntactic compounds can be combined with a variety of V1
verbs, they are likely to appear irregularly in various V1 þ V2 combinations.
However, both the lexical and syntactic compound verbs were equally
redundant; this is probably because both include a variety of compounds
appearing only once or a few times.
3.2. Classification of Lexical and Syntactic CompoundVerbs in the Newspaper Corpus
In order to examine V2 individual differences in the newspaper corpus further,all 48 compound verbs were plotted on the basis of their entropies and

#

Type

V2 verbs
Japanese

LexicalV1 totaltoken

V1 typefrequency

V1 & V2 token
frequency

Entropy

Redundancy
(%)

295
2,914
543
5,947
1,021
2,354
1,554
1,808
355
1,376
632
4,764
135
2,114
333
609
7,153
110
755
599
253
1,529
6,425
244
460
140
444

1,098,690
45,88064,29253,493
17,9898,906
30,41440,283
20,382
16,929434,024
61,171
14,613
13,41021,434
9,679
8,513
27,164
12,213
4,939
7,527
136,575
19,2601,056
20,528
805
1,614

81
57
44
33
27
19
18
31
15
13
16
14
15
13
11
23
18
12
11
11
10
60
10
7
9
7
6

278
174
119
94
61
45
44
229
33
14
55
25
40
19
12
45
56
23
33
20
58
496
25
13
34
14
14

5.76
5.30
4.66
4.39
4.27
3.81
3.78
3.69
3.68
3.66
3.66
3.62
3.58
3.58
3.42
3.36
3.21
3.13
3.07
3.05
2.88
2.77
2.76
2.57
2.51
2.41
2.35

9.10
9.20
14.73
13.04
10.12
10.34
9.35
25.56
5.88
0.97
8.46
4.83
8.44
3.35
1.19
25.72
22.94
12.63
11.26
11.94
13.29
53.04
17.06
8.62
20.80
14.02
8.98

Phonetickomu
ageru
kirerutorumawaru
tuku
aruku
agaru
tugu
sinu
taterukakaru
kaeru
ireru
sasu
kaesu
deru
komeruotyiru
otosu
orosu
kiru
iru
tobasutukerutaosu
korosuK. TAMAOKA ET AL.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27

V2 tokenfrequency

238

Table 1. Frequency, Entropy and Redundancy of Lexical and Syntactic V1 þ V2 Compound Verbs in the Mainichi Newspaper.

okoruwataruoriru
noborukaesu
hirogeru
watasukudarusiru
awaseru

MeansStandard Deviation
1
2
3
4
5
6
7
8
9
10
11

Syntactic

MeansStandard Deviation

tuzukeru
hazimeru
ausugirumakuruowaru
oeru
tukusunuku
kaneru
eru

1,392
573
431
3,417
91
856
491
124
1,993
1,109

3,506
4,639
10,443
13,1871,487
7,812
48,06814,8162,830
38,142

6
7
7
4
5
4
3
3
5
15

19
41
27
11
23
12
10
15
24
61

2.07
2.00
1.68
1.68
1.61
1.42
1.36
1.27
1.14
0.88

19.76
28.81
40.21
16.16
30.68
29.09
14.13
19.69
50.96
77.38

1,496
1,804

63,154
186,738

17.57
17.14

62.59
92.97

2.97
1.14

18.43
15.51

5,519
2,983
2,302
3,777
86
1,884
503
687
575
328
4,478

539,169
1,379,861
295,787
368,408
708,256
51,545
850,402843,270
724,584
1,062,433
362,068

2,102
1,786

653,253
362,723

261
207
170
130
32
31
24
26
23
18
100

1425
657
873
515
66
56
37
89
131
108
1601

6.73
6.50
6.16
5.71
4.56
4.50
4.31
3.72
3.11
2.82
0.08

16.21
15.55
16.87
18.74
8.91
9.18
5.90
20.86
31.33
32.27
98.77

92.91
83.07

505.27546.90

4.38
1.86

24.96
24.68

JAPANESE LEXICAL AND SYNTACTIC COMPOUND VERBS

28
29
30
31
32
33
34
35
36
37

Note. 48 V2 verbs were selected from the pool of 88 lexical compound and 21 syntactic compound verbs on the baseline of more than 10
token frequencies out of 88,454,573 words in the Maichini Newspaper.

239

240
K. TAMAOKA ET AL.

Fig. 2. Plotting and cluster of lexical and syntactic compound V2 verbs based on entropy and redundancy calculated from the corpus of theMainichi Newspaper.
Note 1: Hierarchical cluster analysis using Ward’s method with the square Euclidean distance formed three clusters.
Note 2: 48 lexical and syntactic compound V2 verbs in this figure were selected from the pool of 109 having more than a token
frequency of 10.
Note 3: Verbs in unshadowed boxes are lexical compound verbs (n ¼ 37), while verbs in showed boxes are syntactic compoundverbs (n ¼ 11).

JAPANESE LEXICAL AND SYNTACTIC COMPOUND VERBS

241

redundancies as depicted in Figure 2. A hierarchical cluster analysis using
Ward’s method with the square Euclidean distance produced three clusters as
indicated by the circles in the figure.
3.2.1. Cluster I
A majority of 38 compound verbs are included in Cluster I. Syntactic
compound verbs are likely to be higher in entropy than lexical ones in this), sugiru
cluster. In fact, V2 verbs of syntactic compounds such as au (), hazimeru () and nuku () are very high in entropy,(
suggesting a wide variety of two verb combinations. Although two V2 verbs,) and ageru (), are lexical compounds, they also showed akomu (
wide range of verb combinations. Komu is usually interpreted as ‘‘internal
movement’’ as in nagare þ komu (appearing three times, ‘‘flow into’’),sosogi þ komu (two, ‘‘pour into’’) and kake þ komu (one, ‘‘run into’’).
Although Himeno (1999) classifies these compounds into a type of ‘‘internal
movement’’, V2 komu seems to add the meaning ‘‘to do thoroughly’’ to V1
verbs, such as oboe þ (19, ‘‘teach’’ þ), kezuri þ (13, ‘‘shave’’ þ), utai þ (five,‘‘sing’’ þ), yomi þ (three, ‘‘read’’), and migaki þ (two, ‘‘polish’’ þ) with avery high frequency. Kageyama (1993) pointed out that komu adds a certain
meaning as does a prefix in English, when it is added to various V1 verbs to
produce a variety of compound verbs, and yet these compounds are lexical.
Similarly, the original meaning of ageru, ‘‘lift’’ or ‘‘elevate’’, is extended toinclude ‘‘climb up (as in one’s status)’’, ‘‘something rising up inside thebody’’, ‘‘completion of action’’ and ‘‘emphasis’’ (Himeno, 1999), resulting in
the verb having many combinations with a wide range of V1 verbs.
3.2.2. Cluster II
Cluster II includes eight V2 verbs; two syntactic compounds of kaneru) and tukusu (), and six lexical compounds. All these verbs in(
Cluster II seem to be more redundant than those of Cluster I, especially kiru
) and siru (). There are a wide range of V2 kiru combinations with V1(
verbs; 26 compound verbs with kiru appear just once and 13 compounds
twice. Kiru adds three basic meanings of ‘‘cut or end’’, ‘‘completion’’, and‘‘limitation’’ to V1 verbs (Himeno, 1999). Although kiru is commonly
understood to mean ‘‘cut’’, this was seldom used in the newspaper corpus,
whereas the meaning ‘‘completion’’ was recurrent, such as nari þ kiru (27,‘‘identify completely’’), mamori þ kiru (14, ‘‘defend completely’’), watari þkiru (seven, ‘‘cross completely’’), uri þ kiru (seven, ‘‘sell completely’’), and242

K. TAMAOKA ET AL.

nobori þ kiru (seven, ‘‘climb completely’’). Unlike kiru, siru only has fivedifferent compounds; ukagai þ siru (‘‘ask to know’’) appears 19 times whilefour other compounds appear once or twice. Nevertheless, kiru and siru sharethe similar tendency whereby one or few compound verbs appear frequently,
while many others appear only once or twice.
3.2.3. Cluster III) and the V2 syntactic compound
The V2 lexical compound awaseru () were classified in Cluster III. These two V2 verbs showed a greater
eru (pattern of defilement than others. Awaseru produced 15 different compounds
in the corpus. Among them four lexical compound verbs appeared frequently:
20 times for kangae þ awaseru (‘‘to put thought together’’), 11 times forsuri þ awaseru (‘‘rub things together’’), 10 times for tunagi þ awaseru (‘‘tie
things together’’), and six times for terasi þ awaseru (‘‘check things with’’),while the others appeared once or twice. These four frequently seen
compounds could be common expressions in newspapers. V2 eru of syntactic
compounds appeared 1601 times, being combined with 100 different V1 verbs.
The compound of ari þ eru (‘‘can do’’ or ‘‘be possible’’) showed the highest
frequency, counting 865 times. The compound of nari þ eru (‘‘be possible tobecome’’) was the second, appearing 194 times. This diversity might be as theresult of the fact that eru acts like the auxiliary verb ‘‘can’’ in English.

4. FREQUENCY, ENTROPY AND REDUNDANCY OF COMPOUNDVERBS FROM THE NOVEL COLLECTION
The corpus of Aozora Bunko collected various novels from the periods of Meiji,
Taisho and the beginning of Showa. The collection was gathered from novels
and stories written by famous writers, including 18 novels and stories by Kenji
Miyazawa (1896–1933), 14 by Nankichi Niimi (1913–1943), seven by Souseki
Natsume (1867–1916), 11 by Riichi Yokomitsu (1898–1947), 41 by Kyusaku
Yumeno (1889–1936), 105 by Ryunosuke Akutagawa (1892–1927), 19 by
Takeo Arishima (1878–1923), 105 by Osamu Dazai (1909–1948), 14 by Doppo
Kunikida (1871–1908), 22 by Motojiro Kajii (1901–1932), 12 by Kanoko
Okamoto (1889–1939), 28 by Kan Kikuchi (1888–1948) and so on. Thus, thenovel corpus, Aozora Bunko is considered to be an example of older writings inJapanese. The corpus consisted of a total token frequency, 8,370,720 words. As

Table 2. Frequency, Entropy and Redundancy of Lexical and Syntactic V1 þ V2 Compound Verbs Taken from the Aozora Bunko Novel.
#TypeV2 verbs
Japanese

LexicalV1 total token
frequency

V1 typefrequency

V1 & V2 token
frequency

Entropy

Redundancy
(%)

572
603
658
218
1,980
823
311
460
162
368
150
182
193
678
358
210
86
50
34
287
63
67

25,03728,58635,298
7,413
6,355
4,436
109,842
33,21624,00413,012
21,21645,8809,719
20,161
48,145
6,852
20,96130,796
1,603
2,702
2,581
14,421

48
46
41
28
31
27
36
37
29
23
20
62
20
23
19
15
15
12
12
12
11
10

92
90
107
57
61
45
69
142
79
34
25
174
39
55
36
31
30
15
16
17
20
20

5.13
5.08
4.78
4.48
4.46
4.43
4.42
4.39
4.31
4.26
4.21
4.19
4.16
4.15
4.04
3.55
3.51
3.46
3.45
3.29
3.22
3.18

8.17
8.01
10.75
6.77
9.95
6.92
14.52
15.69
11.24
5.91
2.51
6.10
5.28
8.28
4.95
9.24
10.24
3.58
3.69
8.31
6.87
4.15

Phonetic
ageru
kakarutuku
tateru
deru
toru
kiru
noborumawaru
aruku
sasu
agaru
kaesu
ireru
korosuotyirutukeruawaseru
taosu
ireru
kuruu
orosu

JAPANESE LEXICAL AND SYNTACTIC COMPOUND VERBS

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22

V2 tokenfrequency(continued)

243

244

Table 2. (continued).
#TypeV2 verbs
Japaneseyaburukudasuwataru
kaeru
komu
okosu
kesu

Syntactic

MeansStandard Deviation

V1 typefrequency

V1 & V2 token
frequency

Entropy

Redundancy
(%)

74
102
157
67
281
53
47

3,688
21,0568,438
7,444
110,771
5,335
706

10
9
12
9
81
5
3

14
10
30
42
220
15
13

3.18
3.12
3.11
2.62
2.13
1.93
1.55

4.21
1.51
13.39
17.50
66.48
16.87
2.30

320
381

23,09227,019

24.34
17.68

55.10
50.24

3.72
0.89

10.12
11.48

294
268
617
146
551
84
20
64

148,945
133,453
67,03348,805
159,594
121,923
80,821
17,183

100
85
66
50
98
44
10
12

178
173
132
85
297
79
11
24

6.07
5.72
5.44
5.28
5.12
5.02
3.28
2.98

8.67
10.71
10.08
6.51
22.56
7.99
1.33
16.89

256
210

97,22047,983

58.13
33.24

122.38
87.75

4.86
1.05

10.59
6.08

Phonetic

MeansStandard Deviation
1
2
3
4
5
6
7
8

V1 total token
frequency

hazimeru
ausugirutuzukeru
eru
kanerutukusuowaru

Note. 37 V2 verbs were selected from the pool of 88 lexical compound and 21 syntactic compound verbs on the baseline of more than 10
token frequencies in 8,370,720 words from the collection of Aozora Bunko novels.

K. TAMAOKA ET AL.

23
24
25
26
27
28
29

V2 tokenfrequency

JAPANESE LEXICAL AND SYNTACTIC COMPOUND VERBS

245

with the newspaper corpus, using a baseline of more than 10 token frequencies,a total of 37 V2 verbs were selected from the pool of 88 lexical compound and21 syntactic compound verbs (108 V2 candidates).
4.1. Comparison of Lexical and Syntactic Compound Verbs
As with the newspaper corpus, the ANOVA on entropy indicated that thelexical compound verbs (n ¼ 29, M ¼ 3.72, SD ¼ 0.90) were significantly
lower than the syntactic compound verbs (n ¼ 8, M ¼ 4.86, SD ¼ 1.12)[F(1, 35) ¼ 9.14, p < .01]. In contrast, the ANOVA on redundancy indicatedno significant difference between the lexical compound verbs (n ¼ 29,
M ¼ 10.12, SD ¼ 11.68) and the syntactic compound verbs (n ¼ 8, M ¼ 10.59,
SD ¼ 6.50) [F(1, 35) ¼ 0.01, n.s.]. These results also suggested that V2 verbsof the syntactic compounds were irregularly combined with various V1 verbs
rather than with V2 verbs of the lexical compounds, while both the lexical andsyntactic compound verbs were equally redundant.
4.2. Classification of Lexical and Syntactic Compound Verbs
To investigate individual V2 tendencies of appearance in the novel corpus
further, all the 37 V2 verbs of lexical and syntactic compounds were plottedbased on their entropies and redundancies as in Figure 3. A hierarchical cluster
analysis using Ward’s method with the square Euclidean distance produced
three clusters as indicated by the circles in the figure.
4.2.1. Cluster I
A majority of compound verbs (29 out of 37) were classified into Cluster I. In
general, syntactic compound verbs were likely to be higher in entropy than
) and ageru
lexical ones in this cluster. The two V2 verbs of kakaru (), which combined with V1 verbs to produce lexical compounds, were(also high in entropy. Ageru was consistently high in entropy throughout boththe corpora of newspapers and novels, while kakaru appeared to be high onlyin the novel corpus. Unlike the 14 different lexical compounds created by V2
kakaru in the newspaper corpus, V2 kakaru combined with 46 different V1 inthe novels. Among them, 28 compounds only appeared once and ten
compounds were used twice. However, a variety of compounds with karaku
seemed to have popular usage in the novels during the Meiji, Taisho, and earlyShowa periods, these compounds might be falling out of use in the modern
Japanese.

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Fig. 3. Plotting and cluster of lexical and syntactic compound V2 verbs based on entropy and redundancy calculated from the corpus of novels.
Note 1: Hierarchical cluster analysis using Ward’s method with the square Euclidean distance formed three clusters.
Note 2: Lexical and syntactic compound V2 verbs in this figure were selected from the pool of 109 having more than a token frequencyof 10.
Note 3: Verbs in shadowed boxes are lexical compound verbs (n ¼ 29), while verbs in shadowed boxes are syntactic compound verbs(n ¼ 8).

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4.2.2. Cluster II)
Cluster II includes seven V2 verbs; two syntactic compounds of eru (), and five lexical compounds. All the verbs in Cluster II
and owaru (were basically more redundant than those of Cluster I. Although V2 eru
was extremely high in redundancy in the newspaper corpus as depicted in
Figure 2, it appeared only slightly apart from the majority in the novel
corpus. Given that eru is used like ‘‘can’’ in English, eru appeared to be
combined with 98 different V1 verbs, having a total token frequency of
297 times.
4.2.3. Cluster III
Cluster III only consisted of komu, being highly redundant. This verb
combined with 81 different V1 verbs, counting up to 220 times of token
frequency. The most frequently used compound, nozoki þ komu (‘‘look
into’’) appeared 37 times. A wide range of compound expressions withkomu might be utilized because its accompanying meaning of ‘‘internal
movement’’ is suitable for describing various actions and emotions in
novels.

5. COMPARING THE LEXICAL AND SYNTACTIC COMPOUNDVERBS IN THE CORPORA OF THE NEWSPAPER AND NOVELS
In order to compare compound verbs in the two corpora, 34 V2 verbs wereselected from overlapped items between Figures 1 and 2. The values of entropy
and redundancy in the novels were subtracted from those in the newspaper.
Based upon these values, they were plotted in Figure 4. Again, a hierarchicalcluster analysis using Ward’s method with the square Euclidean distanceproduced three clusters as indicated by the circles in the figure. The cluster
analysis identified that three V2 verbs deviated far away from the majority ofCluster I. Komu, the only V2 verb in Cluster II, was highly redundant in thenovel corpus as seen in Figure 3. V2 verbs of awaseru and eru were classified
into Cluster III. They were seen to combine with a wide range of V1 verbs. As
explained previously in this study, awaseru adds the meaning ‘‘together’’ to V1
verbs and creates lexical compounds, while eru attaches the meaning of‘‘possibility’’ to V1 verbs as the auxiliary verb ‘‘can’’ in English does to produce
syntactic compounds. Regardless of lexical or syntactic, both V2 verbs, awaseru
and eru were preferred for use in the newspaper as a function of enlarging

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Fig. 4. Plotting and cluster of lexical and syntactic compound V2 verbs based on differences of entropy and redundancy between the
corpus of the newspaper and the novels.
Note 1: Hierarchical cluster analysis using Ward’s method with the square Euclidean distance formed three clusters including
two sub-clusters.
Note 2: Compound V2 verbs (n ¼ 34) in this figure were selected from overlapped items between Figures 1 and 2.
Note 3: Verbs in shadowed boxes are lexical compound verbs (n ¼ 26), while verbs in unshadowed boxes are syntactic
compound verbs (n ¼ 8).
Note 4: Differences were calculated from entropy and redundancy of the newspaper corpus subtracted from those of the novel
corpus.

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249

simple V1 expressions. A majority of 31 V2 verbs were classified into Cluster Iwith two sub-clusters. These two sub-clusters, however, were located close toeach other, so it would be sensible enough to conclude that both lexical andsyntactic compound verbs are used with a similar inclination between thenewspaper and novel corpora with only a few exceptions.

6. CONCLUSION
The present study investigated lexical and syntactic compound verbs using
Shannon’s concepts of entropy and redundancy calculated by frequency datafrom the newspaper and novel corpora. V2 verbs of lexical compounds were
exceeded in number by those of V2 verbs of syntactic compounds. Using thebasis of V2 token frequency (more than 10), V2 verbs for syntactic
compounds were only counted as 11 types in the newspaper and nine types in
the novels, while those for lexical compounds were 37 types in thenewspaper and 29 types in the novels. Comparing these V2 types, syntactic
compounds were higher in entropy than lexical ones. This result suggeststhat V2 verbs of syntactic compounds are more likely to combine with a wide
range of V1 verbs than those of lexical compounds. As depicted in Figure 1,
richness in V1 and V2 combinations for syntactic compounds derived fromthe syntactic structure of a verb phrase, VP1, constructed with a noun phrase
NP-o and a V1 verb. This enables connection with a variety of V2 verbs tocreate a verb phrase VP2.
Moreover, since komu and ageru, which both create lexical compounds,
add a certain meaning, as does a prefix in English, these two V2 verbs also
showed a wide variety of combinations with V1. Comparing V2 verbs in thetwo corpora, awaseru and eru indicated a different pattern of entropy andredundancy in the newspaper corpus while komu differed in the novel corpus.
These exceptional V2 verbs must reflect characteristics of the corpora. V2 eru,
which adds the meaning of ‘‘possibility’’, functions like the auxiliary verb‘‘can’’ in English, and seems to be a favored expression in the newspapers. In
contrast, V2 komu, adds the meaning of ‘‘internal movement’’ like thepreposition ‘‘into’’ in English, and appears to be preferred in the novels due toits enrichment of expression of lexical compounds. In general, the present
study suggests that both lexical and syntactic compounds were used similarlyin the both corpora.

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