Zero Pronouns as Experiencer in Japanese Discourse 
Hiroshi Nakagawa 
Dept. of Electronics and Computer Engineering, 
Yokohama National University, 
156 Tokiwadai, Hodogaya, Yokohama, 240, Japan 
e-mail: nakagawa@ naklab.dnj.ynu.ac.jp 
Abstract 
The process of finding the antecedent of zero 
pronoun, that is indispensable to Japanese 
language understanding, is the topic of this 
paper. Here we mainly concern with dis- 
courses comprising two sentences that are in 
a subordinate relation, especially one of them 
describes the agent's volitional action and the 
other describes the reason of the action. We 
propose basically two new principles: (1) The 
agent of an action should experience a certain 
psychological reason, (2) Predicates report- 
ing someone's psychological state are catego- 
rized into 1) weakly or 2) strongly bound to 
the expected point of view. Combination of 
these principles accounts for some problem- 
atic Japanese zero anaphora, which cannot 
be accounted for by the theories so far pro- 
posed. 
1 Introduction 
Kuno said in \[7\] that in Japanese discourses 
we have to omit as many components in a 
sentence as possible unless we get any ambi- 
guity. In fact more components are omitted 
than expected in actual discourses, because 
we have a rich variety of linguistic appara- 
tuses to be used to communicate unambigu- 
ously. From the computational viewpoint 
identifying the antecedent of zero pronoun, 
which is the omitted part of sentence, is re- 
ally needed. For this several theories have 
been developed. 
Among them we first review the two most 
important theories in analyzing zero pro- 
noun's antecedent in Japanese proposed in 
80's. The first one is Centering theory in 
Japanese proposed by Walker etal \[8\]. 
Each utterance of a discourse has a set of 
discourse entities called forward looking cen- 
ters, Cf. Cf's for one utterance are ranked 
according to their discourse sahence. In 
Japanese Cf's are ranked in the following or- 
der of preference: 
TOPIC>EMPATHY>SUBJ>OBJ2>OBJ 
Now we have the following constraints and 
rules to calculate the backward looking cen- 
ter, Cb, which is regarded as the most salient 
discourse entity picked up from Cf's of the 
previous utterance. 
Constraints and Rules 
For each Ui in a discourse segment UI,...,U,~ 
1. There is precisely one Cb. 
2. Every dement of Cf(U;_I) must be realized 
in Ui. Notice that if the antecedent of zero 
pronoun in U; is known to be one of Cf(U;-1), 
then that Cf is regarded to be realized in Ui. 
3. The center, Cb(Ui) , is the highest ranked 
element of Cf(U;_I) that is realized in U;. 
4. If some element of Cf(Ui_t) is reahzed as 
a pronoun in U;, then so is Cb(U/). 
5. Transition states to decide Cb(Ui) are or- 
dered: Continuing is preferred to Retaining 
is preferred to Shifting-1 is preferred to Shift- 
ing. These states are characterized as follows. 
Here Cp(U~) means the highest ranked Cf(Ui). 
Continuing: Cb(U/_I) = Cb(Ui) = Cp(U/) 
Retaining: Cb(U,_I) = Cb(Ui) # Cp(Ui) 
Shifting-l: Cb(U,_t) # Cb(U,) = Cp(U,) 
Shifting: Cb(U;_~) # Cb(Ui) # Cp(Ui) 
Actually, the antecedent of zero pronoun 
is determined under satisfying all these con- 
straints and rules. This centering mecha- 
nism can account for a very broad range of 
Japanese zero pronoun anaphora. Almost the 
same centering mechanism applies to Italian 
pronominal system successfully \[2\]. 
Acr~ DB COLING-92, NANTES, 23-28 AOl3"r 1992 3 2 4 PROC. OF COLING-92, NANTES, AU~. 23-28, 1992 
Another important theory is Property shar- 
ing theory proposed by Kameyama \[4, 5\]. Her 
theory concerns the interaction between Cb 
and zero pronouns. Consider adjacent ut- 
termaces or a sentence including a subordi- 
nated clause. Two zero pronouns appearing 
distinct utterances or clauses can retain the 
same Cb if they share one of the following 
properties: 1) IDENT-SUBJECT, 2) IDENT 
alone, 3) SUBJECT alone, 4) bott, non- 
IDENT and non-SUBJECT, 5)non-IDENT 
only, 6)non-SUBJ only, where the descend- 
ing order means preference, and IDENT is 
almost the same as, or very near, the empa- 
thy proposed by Kuno \[7\]. Although these 
theories cover a fairly large part of Japanese 
zero anaphora resolution, there still remain 
the problematic cases which can be resolved 
by neither of them. In the following sections, 
we will focus on some of the problematic cases 
and show how to deal with them. 
2 Interactions between 
Ira and Kureta 
We begin with the following discourse. 
Alice ga Betty ni 
(1) Alice-SUBJ Betty-DNr 
Carol no koto wo 
CaroI-GEN-NOM-ACC 
oshie-ta. 
inform- PAST 
' Alice informed Betty about Carol.' 
~),~bj Carol no koto wo 
(I) -SUBJ CaroI-GEN-NOM-ACC 
sinpai si -ta karada. 
be anxious -PAST because 
'Because (\]),~bj was anxious about Carol.' 
¢,ubj "~" Alice 
where the last line, and henceforth, shows 
that the native's intuitive interpretation is 
that there being the only possible antecedent 
of the zero subject O,,,bj, and in this case, it is 
Alice. Both the centering algorithm proposed 
by Walker etal \[1, 8\] and Kameyarua's prop 
erty sharing constraint \[4, 5\] predict Alice ms 
a strongly preferred antecedent of tt, e zero 
subject, O,~bj, of (1). So, they correctly pre- 
dict the native's intuition. Let's look at the 
case where the second sentence of (1) is re- 
placed with the following. 
~),ubj Carol no koto wo 
(2) ~-SUBJ CaroI-GEN -NOM-ACC 
sinpai site -ita karada. 
be anxious being-PAST because 
~Beeause O),,bj was being anxious about 
Carol.' 
\[q~,,bj = Betty\] > \[~)o,bj = Alice\] 
where the last line of the above example, 
and henceforth, indicates the native's intu- 
ition of the order of preference for antecedents 
of ¢0~bj in ease we have more than one possi- 
ble antecedents. 
In (2) both Alice and Betty are the possi- 
ble antecedent of ¢,~bj, even though Betty is 
stronger. Both Betty and Alice can be de- 
rived by the theory in \[8\]. However, since 
Alice is subject, their theory predicts that 
Alice is the prinrary candidate of antecedent 
of/l),ubj. 
This is explained by the well known fact 
that "ita"-sufllx, which is used in the second 
sentence in this case, describes the event from 
an outsider's point of view, which, presum- 
ably, makes the antecedent of zero subject 
of "ita"-suilixed verb not be the linguistically 
salient expressions, in this case, the subject of 
the first sentence but be some other person. 
Therefore the zero subject ~°~bj tends not to 
corefer with the subject of the first utterance 
Alice which is a linguistically salient expres- 
sion. As the result #,~j tends to corefer with 
Betty. Basically this explanation comes from 
Kameyama's accounts in \[4\]. 
Look at the discourses whose first sentences 
are the saute as the tlrst sentence of (1) and 
second sentences are the following sentences 
respectively, in which each of the second sen- 
tences describes not a psychological state but 
a physical action of meeting. 
(a) 
~,.bj Kinon eki de 
4) -SUBJ yesterday station-LOC 
Carol to at-ta karada. 
Carol-OB,I meet-PAST because 
'Because (l)°~bj met Carol at the station 
yesterday. 
q)aubj = Alice 
(1),~bj Kinou 
(4) (I~ -SUBJ yesterday 
eki de Carol to 
station-LOC Carol-OBJ 
atte-ita karada. 
be-PAST meeting because 
AcrEs DE COLING-92. NANTES. 23-28 AOUr 1992 3 2 5 PROC. OF COLING-92. NANTES. AUG. 23-28. 1992 
'Because 49,~b./was meeting Carol at the 
station yesterday.' 
\[49°,b~ = Betty\] _> \[49,,bj = Alice \] 
Nevertheless the contents described in the The 
second sentences are categorically different is: 
ones, these two series of discourses, say (1)(2) 
and (3)(4) respectively, show the similar pref- 
erences for ¢,,bj. Therefore the tentative 
summarization of preference mechanism so 
far is the following. 
Principle 1 (Preference(tentative)) 
Consider a discourse of two sentences or a 
complex sentence in which one of the sen- 
tence or clause describes the action taken by 
an agent, and the other sentence or clause 
provides the reason of the action respectively. 
i. As a default, a zero subject of one sen- (8) 
fence or clause that describe the rea- 
son corefers with the subject of the other 
sentence (clause) unless there is a non- 
subject topic in the other sentence (or 
clause). 
2. When "ita"-sufflxed verb is used in one 
sentence or clause that describes the rea- 
son, their zero subjects tend not to core- 
fer with the (topic} subject of the other 
sentence ( or clause}. 
3 Problematic 
Cases, "ita-morat-ta" 
Combination 
Let's compare the following three discourses 
which consist of two sentences respectively, 
and whose first sentences are common one 
shown as follows: 
Betty ga Alice ni 
(5) Betty-SUBJ Alice-bAT 
Carol no koto wo 
CaroI-GEN-NOM-ACC 
oshiete -morat-ta. 
inform -CAUS-PAST 
'Betty i let Alice inform herl about 
Carol.' 
The second sentence of the first discourse is: 
49,~bj Carol no koto wo 
(6) 49 -SUBJ CaroI-GEN-NOM-ACC 
sinpai site -ita karada. 
be anxious being-PAST because 
~Becanse 49,~,j was being anxious about 
Carol.' 
\[49°~b~ = Betty\] > \[~,,bS = Alice\] 
second sentence of the second discourse 
(b,~bj Carol no koto ga 
(7) • -SUBJ CaroI-GEN-NOM-OBJ 
kininatte-ita karada. 
feel anxiety -being-PAST because 
'Because 49,~bj was feeling anxiety about 
Carol.' 
49,,bj = Betty 
The second sentence of the third discourse is: 
49,~bj Kinou eki de 
49 -SUBJ yesterday station-LOC 
Carol to atte -ita 
Carol-OBJ meet -being-PAST 
karada. 
because 
'Because (I),~j was meeting Carol at the 
station yesterday.' 
\[49,,bj = Alice\] > \[49,,sS = Betty\] 
These discourses all have the same "morat- 
ta" -suffixed and "ita "-suffixed verbs followed 
by "karada" cornbination in the first and 
the second sentence respectively. In "oshie- 
te-morat-ta", "(te)-morat" causativizes the 
verb, namely the agent of the action of asking 
some action to other one is the antecedent of 
the subject, and, the more important point 
is that "morat-ta"-suffaxed verb describes the 
action from the subject's point of vicw. As 
the result, in these discourses the empathy lo- 
cus of the first sentence is Betty. While they 
are almost identical in grammatical struc- 
tures, the preferred antecedents of zero sub- 
ject (I),~b./ are quite different. Therefore this 
difference is expected to comc from the con- 
tents of verb phrase of the second sentences. 
First we consider the preference of zero sub- 
ject based on "morat-ta"- "ita" combination. 
Since Betty is not only the subject but also 
the empathy locus of the first sentence, and 
"ita"-suffixed verb describes the event from 
the outsider's view point, namely, from non- 
empathy locus, Alice should be preferred as 
the antecedent of zero subject of the second 
sentence. Although this expectation coin- 
cides with the actual preference of (8), it does 
not with that of (6) or (7). This discrepancy 
cannot be explained by any syntactic theory, 
ACI'ES DE COL1NG-92. NANTES, 23-28 AOUT 1992 3 2 6 PROC. OF COLING-92, NANTES, AUa. 23-28, 1992 
because (6), (7) arid (8), all have the iden- 
tical syntactic structure. Neither the pro- 
posed centering theories \[1, 8, 4, 5\] nor our 
tentative preference principle 1 can account 
for this phenomena. The reason is that (1) 
timy use only the notions of topic, empathy, 
and the effect of 'Sta" and "morat-t£'-suffix, 
(2) all these discourses are the same in these 
notions and suffixes. To explain this discrep- 
ancy, hopefully, in more unified fashion in or- 
der to be able to apply the resulting theory 
to a variety of cases, is the real aim of the 
paper. 
4 Experiencer and Agent 
of Action 
It is cognitively reasonable to assume that 
when a human agent takes a volitional action 
it should be the case that the agent has a cer- 
tain psychological reason. This assumption is 
exemplified, for instance, in the following dis- 
course. 
(9) 
John wa \[¢,~b inu; ga 
John-TP-SB \[(1) -SUBJ dog i -OBJ 
kowakat4a node \] 
fear-PAST because \] 
~obj,~ oi harat-ta. 
(I); -OBJ make-PAST away 
'Because John feared the dog~, he made 
itl away.' 
~,,a, = John 
Clearly and intuitively the antecedent of 
zero subject of the subordinated clause is 
John who is the topic subject of main clause. 
The subject of the main clause should have 
the psychological reason of iris volitional ac- 
tion, oi harat (= make (I) away , (where 
= the dog) ), and the subordinated clause 
states that John experienced a certain fear. 
The intuition of John being the antecedent of 
the zero subject supports the assumption that 
the agent nmst have the psychological reason. 
In other words, the agent of his/her volitional 
action must be an experieneer of the psycho- 
logical state which should be the reason for 
that action. On the contrary in the following 
discourse the agent of the action, boku (- I), 
is not identical with the experiencer of fear, 
say, John. Its unacceptability endorses the 
above assumption. 
\[ John ga inu wo 
(10) * \[ John-SB dog-OBJ 
kowakat-ta node \] boku ga 
fear-PAST because \] I-SUBJ 
~b~ oi harat-ta. 
-OBJ make-PAST away 
'Because John feared the dogl, I made it; 
away. ' 
¢obj = inu(=the dog) 
However if John's fearing can be recognized 
by some other person through observing it, 
and the agent of the action coincides with this 
person, the discourse is acceptable as exem- 
plified in the following examl)le. 
(11) 
\[ John ga inul wo kowakat-ta 
\[ John-SB dog; -OBJ fear-PAST 
you-na node \] boku ga 
seem because \] I-SUB 
~obj,; oi harat -ta. 
¢; -OBJ make away -PAST 
'Becanse John seemed to fear the dogi, I 
made it; away.' 
In this case "you-rid' used in the subordi- 
nated clause makes John's fearing ("kowakat- 
ta") state t)e observed from not John but 
some other not yet specified person, say, X. 
Actually after reading the main clause, we 
know that the. agent of the action is the male 
speakcr, 1 (= boku), and can infer that the 
observer X coincides with I consistently t)eo 
cause X haz not yet had any particular refer- 
eat. That is why (l 1) is acceptable. And this 
acceptability is accounted h)r by the above 
assumption. Through the careful examina- 
tion about the actual discourses, we also con- 
firmed that all these kind of phenomena are 
correctly ot)served even in the case that two 
consecutive sentences are in a subordination 
relation, say, one describes an action taken 
by the agent attd the other gives the reason 
of that action. Now we have conlirmed the 
assumption posed at the beginning of this 
section with some elaborations done in the 
previous lines, so we state it ~.s the following 
principle. 
Definition 1 (Experiencer) Ezperiencer 
is defined as a person who directly experiences 
. certain psychological state in his/her own 
mind. 
AcrEs DE COL1NG-92, Nn~rrES, 23-28 AOUT 1992 3 2 7 Pgoc. ov COLING-92, NA/,ZFES, AUG. 23-28. 1992 
Definition 2 (Observer) Observer is de- 
fined as a person who, from his/her point of 
view, recognizes some other experieneer's psy- 
chological state by observing that experieneer. 
Principle 2 (Agent is Exp. or Obs.) 
Consider a discourse in which the subordi- 
nated sentence (or clause) expresses a psycho- 
logical reason of the volitional action taken by 
an agent which main sentence (or clause) de- 
scribes. The agent who takes the volitional 
action should be either the experiencer or ob- 
server of the situation described in the subor- 
dinated sentence (or clause). 
This principle, superficially, seems to be a 
kind of commonsense inference rule. How- 
ever, since it comes from the very nature of 
human behavior so deeply, it should be re- 
garded as the control hueristics in cognition. 
Now we restate the effect of "ita"-suflix in 
terms of this principle. Consider the following 
examples. 
(12) * \[ Bill wa onaka ga sui-ta 
Bill-TPoSB be-PAST hungry 
node \] boku wa 
because \] I-SUBJ 
hitokire no pan wo yat-ta. 
a piece of bread-OBJ give-PAST 
'Because Bill was hungry, I gave him a 
piece of bread.' 
This sentence is unacceptable or at most 
marginal because of discrepancy of the agent 
of action and the experiencer. In Japanese, 
even if we consider an observer, he/she could 
not be the agent of action when the experi- 
ence, for instances being hungry or being sad, 
is not observable from outsiders \[6\]. However 
if we replace verb "sui-ta" with ira-suffixed 
one, "suite-its", shown in the following, Bill's 
hunger is known to be observed from other 
person, in this case Boku(= I) who coincides 
with the agent of action of giving a piece of 
bread. So it does not violate Principle 2. Ac- 
tually the following (13) is acceptable under 
this interpretation. 
\[ Bill wa onaka ga suite-its 
(13) \[ Bill-TP-SB be-PAST being hungry 
node \] Boku ga 
because \] I-SB 
hitokire no pan wo yat-ta. 
a piece of bread-OBJ give-PAST 
'Because Bill was being hungry, I gave 
him a piece of bread.' 
In conclusion, '~ita'-suflix makes the event 
be described from some outsider's point of 
view. Therefore by identifying that outsider 
with the agent of action, the agent becomes 
to be the observer of the state which is the 
reason of his/her vohtional action. 
One of the important issues about Prin- 
ciple 2 is the relation among this principle, 
Kameyama's property sharing and the cen- 
tering algorithm \[8\]. At first glance Princi- 
ple 2 is exemplified linguistically by subject- 
empathy( 'ident' in her term ) sharing \[5\], 
or by the combination of preference for Cb 
(Backward Looking Center ) continuing and 
Cf Ranking \[8\]. Actually sometimes it is the 
case. However Principle 2 is based on the 
very nature of human behavior. Therefore it 
generally provides more indirect explanations 
than their theories do. But even in the cases 
their theories do not provide a correct and 
unique prediction, like (6), (7) and (8), Prin- 
ciple 2 would provide a certain guideline as 
will be shown in the following section. 
5 Typology of Predicates 
It's time to explain the discrepancy of inter- 
pretations of (6), (7) and (8) noted in sec- 
tion 3. 
Before mlalyzing (6), (7) and (8), we ex- 
amine the minimal pairs of these in which 
non "ita"-suffixed verbs are used in the sec- 
ond sentences, like the followings: 
(14) 
(15) 
(16) 
(I) ,ubj Kinou eki de 
(I) -SUBJ yesterday station-LOC 
Carol to at-ta karada. 
Carol-OBJ meet-PAST because 
'Because ¢,,bj met Carol at the station 
yesterday.' 
~,~bj = Betty 
(~,,~bj Carol no koto wo 
(I) -SUBJ CaroI-GEN-NOM-ACC 
sinpai si -ta karada. 
be anxious -PAST because 
'Because ¢,~,bj was anxious about Carol.' 
~,ubj = Betty 
¢,ubj Carol no koto ga 
(I) -SUBJ Carol-GEN -NOM-OBJ 
kininat -ta karada. 
feel anxiety -PAST becanse 
Acrv_.s DE COLING-92, NANTES, 23-28 AOUT 1992 3 2 8 PROC. OF COLING-92, NANTES, AUO. 23-28, 1992 
'Because d),,,bj felt anxiety about Carol.' 
• ,,,bj = Betty 
In all cases, the antecedent of the zero sub- 
ject is Betty who is the agent of 'qetting her 
inform" action described in the first sentence 
(5). This fact is one of the consequences de- 
rived by Principle 2. Anyway we can regard 
Betty as the expected point of view, hence- 
forth called POV, in the second sentences, 
say, above shown (14), (15) and (16) and also 
in previously shown (6), (7) and (8). As the 
consequence Betty is expected to be the pri- 
mary candidate of antecedent of zero subject 
¢,~bi in all these cases. 
Now we start to examine the original cases. 
First we examine (8). 
Verb "au" ( meet in English), the stem of 
the verb "atte" used in (8), could describe the 
meeting event from the outside of the agent 
who is actually meeting. In other words a 
meeting action is observed from the people 
around as well as the agent him/herself. Frmn 
the first sentence (5) we know that the agent 
of volitional action is Betty who should have 
the reason of the action in the situation de- 
scribed by the second sentence. In this ease 
the "ita"-suflix is strong enough to take the 
non-agent outsider's point of view, namely 
Alice. As a result Alice took the meeting ac- 
tion and Betty was to be an observer. Since 
it coincides with the intuitive preference, and 
this account relies on Principle 2, we once 
again confirm that principle, llowever the 
preferences of the previously shown (6) and 
(7) are, at first glance, the counter examples 
of the combination of Principle 2 and the lin- 
guistic force of "ita"-suttix. 
Therefore we have to try to find another 
reason to explain these phenomena. We do 
not have any syntactic clue to explain the 
difference of their I)references, because they 
are syntactically almost the same. The next 
thing we should examine is the contents of 
verb phrase in the second sentences. Through 
careful examining of number of verbs and so 
called "subjective adjectives" 1 in sentences 
of this type of structure, we found inductively 
that they are categorized into at least three 
groups ms the followings. 
tFor instance, "Kmtasii"(be sad) is regarded as a 
subjective adjective in Japanese. 
Principle 3 (Predicates Categorization) 
2 
POV Neutral Verb "au" used in (8) is of 
this type. This type of verb describes a 
physical action which can be described 
easily and naturally \[rom the point of 
view of anyone around the agent of this 
action, of course including the agent 
him/herself. As the consequence, the 
agent of the action described by this type 
of verb can be interpreted fully under the 
control of "ita"-suJJix' s force. 
Weak POV Bound Verb "sinpai-suru" (be 
anxious) used in (6) is of this type. This 
type of verb describes tile psychological 
state of the agent who takes a volitional 
action, primarily from the expected point 
of view, namely that agent. However 
that state can be observed by other peo- 
ple. As a result, it is possible to de- 
scribe the agent's psychological state ei- 
ther from the expected current point of 
view or fi'om the outside observers. 
Strong POV Bound Verb "kininaru" (feel 
anxiety) used in (7), so called subjec- 
tive adjectives, that express a psycho- 
logical state~ like "ureshi-i"(be happy), 
"kanashi-i" (be sad}, "X-wo-kanziru" (feel 
X) where X is a noun which represents 
a certain psychological state, and so on 
are oJ this type. This type of predicate 
describes an agent's inner psychological 
state that cannot be observed by other 
people. As a result, they describe those 
states exclusively fi'om tile expected cur° 
rent point of view, who is to be the agent 
of the action. 
By combining this categorization and Prin- 
ciple 2 we can account for the discrepancy of 
preference among (6), (7) and (8) as follow- 
ing. 
The preference of (8) has been already ac- 
counted for in this section, which actually 
uses the nature of POV Neutral Verb, "au". 
2The dill'create similar with that of between Weak 
a:nd Strong POV Bound predicates has already been 
observed in the context of antecedent binding through 
Japanese long distance reflexive 'zibun' hi terms of 
three notions, say, SOURCE, SELF and PIVOT by 
Iida and Sells \[3\]. Kinsui \[6\] proposes the framework 
that categorizes aapaalese verbs aatd subjective adjec- 
tives into the similar types as ours. 
Ac'll~s DE COLING-92, NANTES, 23-28 AO~" 1992 3 2 9 PROC. OF COLING-92, NANTES, Air6.23-28, 1992 
Notice that due to the first sentence (5) the 
agent of volitional action "oshie-te-morat" 
(let her inform) is known to be Betty who 
should have the reason of the action in the 
situation described by the second sentence 
(6). By Principle 2 (6) describes Betty's ex- 
perience that causes her volitional causative 
action "oshie-te-morat?' As a result the 
antecedent of the zero subject is primarily 
Betty. However since verb "sinpal-suru"(be 
arudous) of (6) is Weak POV Hound, due 
to the effect of "ita"-suffix, it is also pos- 
sible that non agent, in this case Alice, is 
the antecedent of the zero subject. Namely, 
by '~ita"-suffix Alice's state of being anxious 
("sinpai suru') is known to be observed by 
the original agent Betty. Thus the intuitive 
preference is accounted for by the combina- 
tion of Principle 2, "sinpai-suru" being Weak 
POV Bound, and the effect of "ita"-suffix. 
As described in the above ease, Betty is 
known to be the salient agent in the second 
sentence (7). However since the verb of (7) 
"kininaru" is Strong POV Bound, the zero 
subject is exclusively the expected point of 
view, namely the primarily supposed agent 
Betty even though the verb is "ita'-snflixed. 
Thus we account for native's intuitive prefer- 
ence systematically. 
Intrasentential cases are also accounted for 
in the same fashion as we did in the discourse 
cases. However we omit those due to the 
space limitation. 
6 Conclusions 
The centering algorithms already proposed 
account for much broader range of phenom- 
ena than our theory covers. However their 
algorithms themselves cannot account for cer- 
tain types of phenomena, which we observe in 
reason-action type subordinated discourses, 
etc. These cases can be dealt with by Princi- 
ple 2 and predicate categorization especially 
Strong and Weak POV Bound types as stated 
in the following principle. 
Principle 4 In the subordinated sentence or 
clause whose verb describes the ezperiencer's 
psychological state and is Weak PO V Bound, 
as .\[or the antecedent of zero pronoun, the 
non-experiencer expected by the force of "ira"- 
suffixed verb and by Principle ~ can override 
the supposed experiencer. In eases of Strong 
PO V Bound this overriding does not happen. 
Incorporating with these principles, the al- 
ready proposed centering theories could cover 
much wider zero anaphora phenomena. 
Acknowledgments 
I would like to thank Prof. Takao Gunji, Prof. 
Tal~si Iida, Dr. Megumi K~rneyama, Dr. Ya~ 
suhiro Katagiri, Prof. Satoshi Kinsui, Prof. 
Yukinori Takubo, Prof. Syn Tutiya for their 
helpful comments. I Mso thank Prof. Livia 
Polanyi who showed me what an interesting 
field discourse is. Part of this work has been 
done during the author's stay at CSLI, Stan- 
ford University in 1990. This stay is finan- 
cially supported by The Telecommunications 
Advancement Foundation in Tokyo. 
ACRES DE COLING-92, NANTES, 23-28 Aot~r 1992 3 3 0 PRO(:. OF COLING-92, NANTES, AUG. 23-28, 1992 

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\[2\] Eugenio, B. D. :Centering theory and the 
Italian pronominal system, Coling'90, 
1990 

\[3\] Iida, M. and P.Sells :Discourse Factors in 
the Binding of zibun, in Japanese Syntax 
(ed. W.Poser) CSLI, 1988 

\[4\] Kameyama, M., Japanese Zero Pronom- 
inal Binding: Where Syntax and Dis- 
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