Case Revisited: In the Shadow of Automatic Processing of Machine-Readable 
Dictionaries 
Fuliang Weng 
Computing Research Lab, New Mexico State University 
Las Cruces, NM 88003 
This paper discusses the work of automat- experiencer; if a person who uses this concept 
ically extracting Case Frames from Machine- believes that seeing is a process of active selec- 
Readable Dictionaries based on a three layer tion, then this person will assign to its subject, 
a posteriori Case Theory\[5\]. an active Case such as agent. 
The theory is intended to deal with two 3. context layer: in this layer, Cases 
problems: 
1. To dynamically adjust grains of Cases. 
This is where a posteriori comes from. 
2. To provide a procedure to determine 
Cases. This is where three layer comes from. 
The three layers are: 
1. base layer: This layer is intended to ac- 
complish transformations of words to concepts 
by explicating language and word specific im- 
plicants, e.g., for the verb eat in the intran- 
sitive case, its subject is eater, while for verb 
break in the intransitive case, its subject is the 
broken. 
2. default layer: in this layer, implicit as- 
sumptions of naive theories are made explicit, 
e.g., for concept see, there are two different 
views towards its subject: if a person who uses 
this concept believes that seeing is just a pro- 
cess of passive perception, then this person will 
assign to its subject, a passive 1 Case such as 
*I would like to express thanks to Dr. L. Guthrie, 
Dr. D. Farwell and Prof. Y. Wilks for comments and 
encouragement. This project is supported in paxt by 
CRL. Some of the ideas were developed during my stay 
in CS/Fudan and CMT/CMU. 
1The words passine/'acti~e are used to indicate dif- 
ferent levels of activeness. In what follows, Cases 
such as agent and instrument have somewhat different 
meanings than the conventional ones. We use them 
just for referring to a group of phenomena which are 
related to their names. 
are further clarified upon any requests from 
current tasks, associated context and personal 
belief systems (knowledge), e.g., in sentence 
The commander forced the soldier to break the 
door., whether the soldier should be assigned 
agent, instrument, active, or something else, 
should be decided by both contextual infor- 
mation and needs. 
Arguments for the three layer theory can be 
found in\[5\]. 
Relevant knowledge sources for arriving at 
different layers are: 
1. Formation of the base layer: the for- 
mation is based on knowledge sources which 
mainly come from syntactic codes and def- 
initions in LDOCE (Longman Dictionary of 
Contemporary English). Examples in LDOCE 
also contribute to this process \[1\]. 
2. Formation of the default layer: the for- 
mation is based on the assumption that naive 
theories are weakly consistent, which implies 
that certain semantic classifications may be 
consistent with certain naive theories: verb, 
noun, preposition and adjective classifications 
based on semantic and pragmatic codes in 
LDOCE, and examples in LDOCE can help 
to obtain such theories. 
3. Formation of the context layer: the 
unification of the base layer and the de- 
337 
fault layer forms an initial representation of 
the context layer, its further development 
mainly depends on task, contextual needs and 
personal belief systems. The initial repre- 
sentation is a tuple with three components: 
entity-role, environment and endurance. An 
example of an initial representation for break 
is: ((+) (u-) (0)) break ((-) (u-) (0)), where 
(+) stands for active, (-) for passive, (u -) for 
indexing of the internal environment, (0) for 
duration. If the task is MT, the requirement 
for understanding could be shallow as pointed 
out by Wilks \[7\], although he did not discuss 
any dynamic grain adjustment. Contextual in- 
formation can be conveyed by active features 
Following the boot-strapping principle, we 
are starting with 750 genus verbs in the defin- 
ing word list of LDOCE, then gradually ex- 
panding them to all the verbs defined in 
LDOCE. 
There are various subtasks associated with 
this work: 
1. Dynamically adjusting classifications of 
relational concepts (mainly reflected by verbs): 
we are trying to get a set of core verbs as proto- 
types of classes based on certain statistics and 
genus verb sense nets (the latter is being con- 
structed by G. Stein). A primary set of core 
verbs have been chosen, functional verbs are 
carefully prevented. The criterion for dynam- 
ically adjusting verb classes is: Cj (d) = (y : 
II y-z H< d,z E Cj), where C i are core classes 
and II • II is defined as: II y-x U = mini( i is the 
numbers of links on P, P is any path connect- 
ing x and y }. We can select a reasonable dis- 
tance for Cj(d) by detecting slopes with points 
in the distribution of members. Classification 
can also be done within connectionist models. 
2. From the prototypes, naive theories may 
be formed, and then converted into represen- 
tations in the default layer. 
3. Dynamic creation of Cases. Initial rep- 
resentations in the context layer may be ad- 
justed and new Cases be created according to 
a set of contextual conditions (mainly when 
mismatches happen). 
4. A set of rules can be constructed to get 
the conventional Cases for typical situations. 
Many Case Theories are focused on verbs. 
In our situation, all the four major cate- 
gories (verb, noun, adjective and preposition) 
must be paid enough attention to, since there 
are many verbs defined by verb phrases in 
LDOCE. e.g., a definition entry of verb take 
in LDOCE contains get possession of. In or- 
der to select a right Case frame and verb class 
for each verb, we need something beyond what 
we have presented although it does not con- 
flict with what we have proposed and it is very 
plausible that the procedure used here may be 
adapted to establish Case frames for nouns, 
adjectives and prepositions. This task may be 
benefited from \[2\]. 

References 
\[1\] B. Atkins et al, Explicit and Implicit In\]ormation 
in Dictionarien, CSL Report 5, Princeton Univer- 
sity, 1986. 
\[2\] R. Bruce and L. Guthrle, GenuJ Disambiguation: 
A Study in Weighted Prelerenee, MCCS-91-207, 
CRL/NMSU, 1991. 
\[3\] C. Fillmore, The Ca~e \]or Case,in Uni~ersab in 
Linguistic Theory, E. Bach and R. Harm (eds.), 
Holt, Rinehart, and Winston, 1968. 
\[4\] R. Schank, Coneeptaal Information Processing, 
North-Holland Publishing Co., 1975. 
\[5\] F. Weng, A Three-Layer a posteriori Ca~e The- 
07, in preparation, 1991. 
\[6\] W. Wilkins, Syntaz and Semantics, Academic 
Press, Inc., California, 1988. 
Y. Wilks, An Artificial Intelligence Approach 
to Machine Translation, in Computer Models o\] 
Thoaght 6nd Language, R.Schaak and K.Colby 
(eds.), W.H.Freemaa Co., 1973. 
