I OIO~S :iN THE ROSETTA MACHINE TRANSLATION SY.~TEM
Andr~ Schenk
Philips Research Laboratories
Eindhoven, The Netherlands
Abstract
This paper discusses one of the problems of machine
trans\].ation, n.m~mly the translation of idioms. The paper
describes a solution to this problem within the theoretical
framework of the Rosetta machine translation syst~n.
Rosetta is an experimental trans\] at\]on system which uses an
intermediate lard,mate and translates between Dutch, English
and, in the future, Spanish.
I ~nt roduet ion
Idioms have been told still are a basic theoretical sttnlb-
ling block in most linguistic theories. For the purposes of
machine translation or, in genera\], natural language pro-
cessing, it is necessary to Ix~ able to deal with :idioms
because there are so i~any of th~n in every language and
because they are an essential part of it.
ldioms occur in sentences as a number of words, possibly
scattered over the sentence and possibly with sonde inflec-
ted el~nents; this ntnfl~er of words has to be interpreted as
havip4~, one primitive meaning. For example, in (1) "nade",
"peace" and "~.Rth" have to be interpreted idlomatically.
Note that words that are part of the idJ~n are underlined.
(1) lie has made his peace with his neighbour
The classic example Is (2):
(2) Pete kicked the bucket
Literally this sentence means that Pete hit a specific
vessel ~¢\[th his foot. In the idiomatic reading the inter-
pretation is that Pete died. It is impossib\]e to infer this
idiomatic meaning directly fron the prlm~tives "Pete",
"kick", "the" and "bucket" and from the way they are
eomblned.
Idioms can undergo sy~itaetie transformations, but sometimes
they are reluctant to do so. The passive sentence (3) has
lost its idiomatic reading, while in the ~assive sentence
(4) the idiomatic reading has heen retained .
(3) The bucket was kicked by Pete
(4) Mary's heart was broken by Pete
Other examples are (5-12). In the idiomatic reading in (5)
clefting with the object as focus is not allowed, while it
is allowed in (6) if "Mary" is stressed. Clefting with the
subject as focus in both (7) and (8) is permitted. In (9)
the PP "at whose door" and in (I0) the NP "whose heart" can
be subject to wh-movement. In (ii) the NP "Mary's heart"
can be topicallzed (if "Mary" is stressed), but in (1.2) tbe
NP "the bucket" cannot undergo this transformation without
losing the idicanatic reading. Thus idioms behave syntacti-
cally like non-idiomatic structnres, although sometimes
they are restricted .
(5) It was the bucket that Pete Idcked
(6) It was Mart's heart that Pete broke
(7) It was Pete that kicked the bucket
(8) It was Pete that broke Mary's heart "
(9) At whose door did Pete lay his failure
(i0) those heart did Pete say that Mary broke
(ll) Mary's heart Pete broke
(12) The bucket Pete Icicloed
Idioms can take free arguments or can have elenents, llke
possessive pronotms, which have to be hound hy arguments.
In sentences (13-1.5) "Mary" \].s a complement to the idio-
matic verb, and realizes different grammatical functions in
the sentence (i.e. indirect object, possessive NP and to-PP
object respectively)° In (16) the pronoun "his" has to Im
bound by the subject "l?ete".
(13) Pete gave Mary the finger
(14) Pete broke Mary's heart
(15) Pete Laid down the law I:o Mary
( 16 ) Pete _19st -hi s .t_empe_r_
l.ingtdstic theories on idioms should he able to account for
the prohibits out\]\]ned above. The proposals made are usually
fragmentary, ill the sense that they only are concerned with
part of the probl~n, for instance Fraser (1970), who only
deals with the possible application of transfo~vaations to
idioms, or they are a relatively minor part of a larger
theory, for example Chomsky (1981.), who gives a very
general and prfneipled account of idioms, Nit cannot cope
with all the data. More elaborate studies on idioms are
usually not directly relevant to machine translation, for
instance Boisset (1978), who treats idioms frc~n a more
pragm~qtic lYoint of view. To illustrate it could be argued
that Chomsky (1981) can cope with sentences such as (2) and
(15), but not wtt:h (13), (1.4) and (16); Pesetsky (1985) can
deal with (2) or (13-16), hut not with a sentence lilm:
(17) Pete lald his failure a:t Mary's d_oo ~
Chonsky (198\[, p. 146, note 94) claims that "we may think
of an idiom rule for an idiom with a verbal head as a rule
adding the string aVc to the phrase marker of each terminal
string abc, ~dmre b is the idiom, now understanding a
phrase marker to be a set of strings" and that idioms
"appear either :In D-structure or S-strncture or LF-form."
Furthermore "at: D-structure, idioms can be distinguished as
subject or not snhject to Move alpha".
Thus here it is possible to reanalyse a string abe ~nto aVc
as for example for sentence (2) in figure (18), where the
reanalysis is indicated by a double tree and where a is
"Pete", b is "kick the bucket" and c is empty:
(1.8) s
VP
NP
Pete
kick
f /
V
It seams that on this approach ele~tents of idioms must be
adjacent at a certain level (D-structure, S-structure or
LF-form), which is the case for sentence (2). ttowever, in
sentence (14) the parts of the idiom "breok" and "heart"
are not adjacent at any level, since the free argument
"Mary" is situated between the idiom parts and in (16)
"lose" and "temper" are not: adjacent at any level either.
IIence this theory is not able to deal with every type of
idiom.
319
According to Pesetsky (1985) in a configuration such as
figure (19) B and E may undergo a rule of idiosyncratic
interpretation, if E is the head of C.
A
(19)
B C
E
For sentence (14) in which "heart" is the head of the NP
dominating '~ury's heart", the Me of idtosyncratie Inter-
pretation is allowed, resulting in:
S
D
(20)
specific configuration proposed by Pesetsky.
In the field of compntational linguistics not much atten-
tion has been paid to idioms. Some examples are Rothkegel
(1973) and Wehrli (1984). However, in their proposals
idioms are treated in the lexicon or morphology and there
is no apparent way to account for the scattering of
elements of idioms in sentences.
The organisation of the rest of the paper is as follows: in
section (2) an outline of the theoretical framework of t|~
Rosetta machine translation system will be given; section
(3) discusses idioms within this frmuework; section (4)
discusses some of the typical problems mentioned in the
introduction.
NP VP
Pete
V NP
break~ ~
i Np
; ~
: Mary's
V
In the above tree, the effect of
interpretation is indicated by the dotted lines; the effect
is that the idiom parts are mapped onto one meaning.
As snggested by Pesetsky, this would also account for
sentence (13) if we follow F~yne (1982) in his analysis of
double object constructions. Kayne claims that "NP the
finger" forms a constituent with "the finger" as its head,
so the rule of idiosyncratic interpretation is allowed.
Sentences (17) and (21-22) are problematic even under this
analysis:
(21) Pete rammed his lack of money down Mary's throat
(22) Pete gave Mary credit for her work
Figure (23) gives a representation of sentence (21) in
which "his lack of money" and "Mary" are free arguments:
(23) S
Pete
his lack of money P NP
down ~
NP
Mary's
Since "throat" and "down" are heads of their constituents,
one might suggest a successive application of the rule of
idiosyncratic interpretation, but it is not clear how such
a rule should operate and since every constituent has a
head and syntactic categories are no barrier to rule
application, the domain in which this rule is permitted is
unlimited.
It seems that Chomsky (1981) and Pesetsky (1985) are not
capable of dealing with the counter examples given here.
The treatment of idioms presented in this paper can cope
with these phenomena because it is based on the asst~nption
that elements of idioms neither have to be adjacent at the
level of interpretation nor do they have to be in the
320
N
throat
N
heart
"'
the rule of idiosyncratic
2 Outline of Isomorphic M-Grammars
The Rosetta system is based on the "isomorphic grammar"
approach to machine translation. In this approach a sen-
tence s" is considered a possible translation of a sentence
s if s and s" have not only the same meaning but if they
also have similar derivational histories, which implies
that their meanings are derived in the same way from the
same basic meanings. This approach requires that "iso-
morphic grammars" are written for the languages under
consideration.
The term "possible translation" should be interpreted as
"possible in a particular context". The discussion in this
paper will be restricted to the translation of isolated
sentences on the basis of linguistic knowledge only.
In the following sections the notions M-gremmars, the
variant of Montague grammar used in the Rosetta system, and
isomorphic grammars will be introduced. For a more detailed
discussion of isomorphic M-grammars the reader is referred
to Landshergen (1982, 1984). In section (2.3) an example of
an M-grammar will be given.
2.1 M-Gray, mrs
The grammars used in the system, called M-grammars, can be
seen as a computationally viable variant of Montague
Grammar which is in accordance with the transformational
extensions proposed by Partee (1973). This implies that the
syntactic rules operate on syntactic trees rather than on
strings. Restrictions have been imposed on the grammars in
such a way that effective parsing procedures are possible.
An M-grammar consists of (i) a syntactic, (ii) a morphol-
ogical and (iii) a semantic component.
(i) The syntactic component of an M-grammar defines a set
of "S-trees".
An "S-tree" is a labelled ordered tree. The labels of the
nodes consist of a syntactic category and a list of
attribute-value pairs. The branches are labelled with the
names of syntactic relations, such as subject, head,
object, etc.
An M-grammar defi~es a set of S-trees by specifying a set
of basic S-trees and a set of syntactic rules called
"M-Rule s".
An "M-Rule" defines a partial function from tuples of
S-trees to S-trees.
Starting from basic expressions, an expression can be
formed by applying syntactic rules. The result of this is a
surface tree, in which the labels of the terminal nodes
correspond to words. This process of making an expression
is represented in an M-grammar by a "syntactic derivation
tree', in which the basic expressions are labels of the
terminal nodes and the names of the rules that are
applicable are labels of the non-terminal nodes. In the
example below (Fig. (25)), rule R I makes the NP "the cat"
from the 'basic expression "cat" and rule R 2 makes the
S-tree for the sentence (24) on the basis of the NP and the
basic expression "walk" (the constructions to the left of
the dotted llrms are abbreviations of ~lat the result of
the application of the rule looks like).
(24) the cat is walking
(25) SEN%EN~ ...... R 2
~z_J-- ~'~-- . /X
the cat is walking / ~
~NP ...... R I walk
the cat J cat
(ii) The morp|mlogical component relates terminal S-trees
to strings° This conu~nent will be ignor~l in the rest of
the discussion.
In this way the syntactic and the n~rphological component
define sentences.
(iii) The sem~mtic c~nponent. M-grammars obey the composi-
tionality principle, i.e. every syntactic rule and every
basic S-tree gets a model-theoretical interpretation. For
translation purposes only the names of meanings and the
names of meaning rules are relevant as ~il\] be shown later.
The model-theoretical interpretation of the basic S-trees
and the synt~tic m*les is represented in a "s~lantic
derivation tree", which has the same ~eo~l~try as the
syntactic derivation tree, hut is labelled with naales of
meanings of r~es and basic expressions. An example is
given below in (27).
Before giving an example of an M-gramnmr in section (2.3),
isomorphic M-grm~mars will be discussed.
2.2 Isomorphic M-Grammars
To establish the possible translation relation the gramnars
must be attuned to each other as follows:
- For each basic express:ion of a gr~maar G of a language L
there is at least one basic expression of a grammar G" of a
language L" with the same meaning.
- For each syntactic rule of G there is at least one
syntactic rile of G ~ corresponding to the sane meaning
operation. Syntactically these roles nmy differ consider-
ably.
Two sentences are defined to be (possible) translations of
each other if they have derivation trees with the sm~e
geometry, in which the corresponding nodes are labelled
with names of corresponding rt~es and basic expressions. If
this is the case then the derivation trees are isomorphic
and the two sentences have the same semantic derivation
tree.
Grammars that correspond to each other in the way described
above will be called "isomorphic grammars" if the corre-
sponding rules satisfy certain conditions on application,
such that for each well-fonned syntactic derivation tree in
one language there is at least one corresponding well-
formed syntactic derivation tree in the other language. A
syntactic derivation tree is well-formed if it defines a
sentence, ioe~ if the rules are applicable.
The following is an illustration of these principles= X~e
left part of figure (27) shows the derivation tree of
sentence (26) which is the Dutch trm~slation of sentence
(24). Rule R~ h~ilds the NP "de kat" from the basic
expression "kat' and rule R" 2 constructs the expression "de
kat loopt" from the NP and the basic expression "lopen".
There is a correspondence between both the basic ex-
tree is mapped onto a
derivation tree and each
the corresponding basic
English
......... Itbe cat
cat
syntactic
derivation
tree
syst~n is based on the
pressions and the syntactic rules of the two granmars. Each
rule of the syntactic
corresponding rule of
basic expression is
meaning.
(26) de kat loopt
( 27 ) Dutch
....
de kat I
kat
s~tactic
deriwltion
tree
The Rosetta machine
isomorphic gram~qrs approach. The semantic derivation trees
are used as the interlingua. The analysis cc~ponent trans-
lates sentences into semantic derivation trees; the gener-
ation component translates semantic derivation trees into
target lang~mge sentences. In this paper the translation
relation will ~ discussed generatively only.
2.3 All Example of an M-Gr~mmmar
In this section an example will be given of an M-grammar
that generates sentence (28)i
(28) Pete lends the glrl a book
Only those M-Rules that are relevant to the discussion in
the following sections will be dealt with. Note that the
rules given here are in an info~xaal notation.
The M-gran~nar needed for this exanple:
(i) basic S-trees:
VERB(lend)
(in this infomnal notation the syntactic information in the
basic S-trees, given in the focal of attribute-value pairs,
has been omitted)
NOUN(Pete)
NOUN(girl)
NOUN(book)
VAR(xl) , VAR(x~),...
(VAR'§ are s~itactic variables corresponding to logical
variables)
(ii) M-Rules:
Some notationa\] conventions:
- tl, t , etc. are S-trees,
mu's ~ndicate arbitrary strings of relation/S-tree pairs,
- square brackets indicate nesting,
- in an expression of the fonn det/ART(the) det is the
relation, ART the category and "the" a literal.
So an expression like CL\[subJ/NP, head/VERB, n~l\] stands
for:
CL
j / "
NP VERB
R I : if t I is of category VERB and
t 2 is of category VAR with index i and
t 3 is of category VAR with index j and
321
derivation
the s~antic
mapped onto
B 1
s~tmntic
derivation
tree
translation
t 4 is of category VAR with index k
then: CL\[subj/t 2 , head/t i , iobj/t " 3 , obj/t 4 \]
The rule operates on a ditransitive verb and three vari~
ables at~d makes a clause in which the variables are the
subject, indirect object and direct object respectively.
R 2 : if t\] is of category NOUN
then:" NP \[head/t i\]
R 3 if t I is of category NOUN
then: NP\[det/ART(the), head/tl\]
R 4 : if t\] is of category NOUN
then: NP\[det/ART(a), head/tl\]
R5 i: if t I is of category NP and~
' t~ is of the form CL\[subj/VAR(xi) , mul\]
then: z CL\[subj/tl, mul\]
This is a rule scheme with an instance for every variable
index i. The rule substitutes an NP for the subject
variable. The same holds for rules R~ ~ and R~ , in which
the NP's are substituted for the indif@.dt and di~ct object
respectively.
R6,j: if t I is of category NP and
t 2 is of the form CL\[mul, iobj/VAR(xj), mu2\]
then: CL\[mul, iobj/t I, mu2\]
~,k: if t I is of category NP and
t 2 is of the fon1~ CL\[mul, obj/VAR(x,.)\]
then~" CL\[mul, obj/t~ \]
if t I has the form ~l,\[s\[tbj/NP, llead/vERB, mull
R8 : then: SENTENCE\[subj/NP, head/VERB, mu\].\]
Apart from changing the category, this rule assigns the
tense to the verb and specifies the form in accordance with
the number and person of the subject, which is not
indicated here (the correct form is spelled out in the
morphological component ).
In this example the rules operate as follows:
-Rule R I applied to "lend", VAR(xi) , VAR(xj) and VAR(Xk)
as indicated,
- rule Rp applied to "'Pete" gives NP(Pete),
- R 3 applied to "girl" renders NP(the girl),
- R 4 applied to "'book" NP(a book),
- rule R 5 { applied to "lend" and NP(Pete) renders CL(Pete
lend x. x~'~, K .,
- appl~cation of R~ . to lend" and NP(the girl) renders
CL(Pete lend the gi~IJx~), ~ i
- application of ~ k fro "lend" and NP(a book) resLtlts in
CL(Pete lend the gir~ a book),
- application of R 8 gives £EhTI~NCE(Pete lends the girl a
book).
~he derivation tree for this example is represented in
(29):
(29) R8~
R7 .k
book "~- J'~""
R
eno x i xj x k
3 Idioms and Isomorphic M-Grammmrs
Pete
Traditionally, in Montague semantics, as for instance in
the PTQ paper (Moutague, 1973), a basic expression has a
primitive meaning. However, the semantic concept basic
expression does not always coincide with what one would
call a syntactic primitive. This is the case, for instance,
with idioms. For exmnple the idiom "kick the bucket" has
the primitive meaning "die', but the syntactic primitives
are "kick", "the" and "bucket".
322
For reasons given in the introduction it is impossible to
treat idioms as strings (i.e. syntactic primitives)° The
possibility of applying syntactic transformations to (el-
oments of) idioms, which are also applicable to non-idio-
matic constructs, suggests that idi~l~s should be treated as
having complex constituent structures, which are similar to
non-ldiomatic constituent structures. The possibility of
having free arguments, which are realized by various
grammatical functions, suggests that parts of idioms do not
have to be adjacent at any level of the syntactic process.
The complex idiomatic constituent structure should accommo-
date this.
In Rosetta, before idioms were introduced, basic ex-
pressions were terminal S-trees, i.e. tenminal nodes.
Idioms can be treated as basic S-trees that have an
internal structure. This type of expression is an example
of what will be called a "comp\]ex basic expression" (CBE).
A CBE is a basic expression from a semantic point of view,
i.e. it correspands to a basic meaning, and a complex
expression from a syntactic point of view, i.e. it is a
non-terminal S-tree. For exmnple, the basic S~tree for
"kick the bucket" looks like the following:
(30) VERB
VERB
"kick" det/~hea d
/ x
ART NOUN
"the" "bucket"
By extending the notion of basic expression in this way the
attuning of grammars (as defined in section (2.2)) is
easJer to achieve: corresponding basic expressions may be
CBE's. For ex~nple the D~itch verb "doodgaan" may correspond
to the English idiom "kick the bucket". Special measures
are necessary to guarantee that the rules obey the condi-
tions on application (cf. section (2.2)).
VAN
V 1
Basic expressions are listed in the basic lexicon of a
grammar. A CBE is represented as a canonical surface tree
structure in the lexicon. A canonical surface tree struc-
ture is the default tree structure for a certain sentence,
phrase, etc., i.e. the structure to which no syntactic
transformations have applied. For example: if there is a
passive transformation, the canonical structure is in the
active form. Figure (32) shows the lexicon representation
of the idiom:
(31) x I lend x 2 a hand
(32) VERB
sub J -. \]~ea~ iob~jbj~j obj
VAR VERB VAR NP
V 1 "lend" V 2 de/~k ~ .. ead
/ \
ART NOUN
"a" "hand"
The VAR nodes are not specified (i.e. not referring to an
actual VAR) in the dictionary. These variables will be
replaced by syntactic variables, when the CBE is inserted
into the syntactic tree, Apart from the category VERB and
the usual attribute-value pairs~ the top node contains a
set of attribute-value pairs that indicates which trans=
formations are possible.
3.1 Treatment of Complex Basic Expressions
In this section an extension of the M-grammar of section
(2.3) will be given that can deal with an interesting class
of Complex Basic Expressions and t~o M-grarmnars will be
related to each other according to the isomorphy approach.
Some other reasons for having complex basic expressions
will be given.
3.1.1 An Example of an M-grmmmar for Complex Basic
Expressions
In this section an M-graml~mr will be presented that
generates the idiomatic sentence:
(33) Pete lends the girl a band
The grmmnar of section (2.3) is extended in tile following
way:
(i) basic S-trees
VERB(V I lend V 2 a hand)
(ii) M-Rules:
R 9 : if t I is of the form VERB\[suhj/VI,
head/~\]U~B, iob~/V~\] and
t 2 is of category VAR with index~i and
t 3 is of category VAR with index j
tllen: CL \[ sub ,. J/t2 head/VERB,• Lobj/t 3 \]
This rule expects a complex, transitive verb and two
variables; it constructs a clause in which tile variables
are the subject and the indirect object.
For this example the rules operate as follows:
- R 9 renders CL(x i lend x. a hand),
R 2 and R 3 as in section3(2.3),
R5 i renders CL(Pete lend x. a hand),
R6'. gives CL(Pete lend theJgirl a hand),
ru~ R 8 results in CL(Pete lends the girl a hand).
The derivation tree for this sentence is represented in the
left part of figure (37).
The . resnlt . . of . application . of rules Rp, R2, R represented a tree structure in figure 3 , R5.i and R is as (34")." 6,j
(34) ~J/¢I CL ~--
NP VERB NP NP
I "lend" A /k
hem\[ det \ head det / head I / • \
NOUN ART NOUN ART NOUN
"Pete" "the''glrl" "a" "hand"
111is construct is slmilar to the construct made after
applying, rule~,~ R. to R 7_~, in the example of section (2.3).
One of the basic expresJions differs. So the structures can
he idiomatic or non-idiomatic and other rules of tlle
M-granmmr (e.g. wh~novement or passiw\[sation) are appli-
cable to both these structures, unless, as In tile case of
certain idioms, they are prohibited as indicated at the top
node.
3.1.2 Complex Basic Expressions and Isomorphic Grammar~
Assume we have an M-grammar that generates the Dutch
sentence (35) wldch is a translation of (33). It is then
possible to let the English M-grammar given above for (33)
correspond to this grmnmar in the following way:
(35) Pete helpt het meisje
"
R"
73
"3 "
Pete help
corresponds to the basic
and "help" to B , rules R 9
2
M 6
M
/~.~ R~ /'k M4
Pete Vla .. V 2 B 1 B 2
Here "Pete" in both languages
meaning B , "V lend V 2 a hand"
1 \].
and R" correspond to meaning rule MI, R 2 and R" 2 to M2, R 5
and R'~ to M4, etc..
In this ~ray it is possible to establish a correspondence
between complex basic expressions in one language and basic
expressions that are not complex in another. In a similar
fashion it is possible to establish a relation between
complex basic expressions in one language and cc~nplex basic
expressions in another. Note that in this way it is not
necessary to incorporate a so-e&lled structural transfer in
the machine translation syst~n for the translation of
CBE" s.
3.2 Other Reasons for Waving Complex Basic Expressions
(36) R
R
73
Expressions that: are not idiomatic, but that consist of
more than one word can be handled by means of a c~nplex
basic expression in order to retain the isomorphy. This is
the case if the expression (i) corresponds to an idiom or
(ii) corresponds to a word in another lmlguage. Examples
are tlle follo~clng:
(i) In l)utch (37) is not an idiom it* the sense defined
above (i.e. the meaning of the expression "kwaad worden"
can be composed in a natural way from "kwaad" and "wor-
den"), but has an idiomatic equivalent in English (38).
(37) kwaad worden (Eng. "become angry")
(38) lose one's temper
If "kwaad worden" has to correspond to "lose one's temper",
then in a technical sense, in Dutch, "kwaad worden" can be
treated in the s~ne way as an idiom.
(ii) The Italian word (39) which translates into F.nglish
(40) and Spanish (41) whieh translates into English (42)
are words that correspond to complex expressions in English
(and Dutch). From a translational point of view cases like
"get up early" can be treated in the same way as idioms.
(39) adagiare
(40) lay down with care
(4\]) madrugar
(42) get up early
4 Some Typical Problems
In this section sonle of the problems mentioned in the
introduction will he briefly discussed.
4.1 Argument Variables Embedded in a Complex Bas:\[c
Expression
In sentence (43) there are two arguments "Pete" arid "Mary"
and the idiom "x. \[ break x_'s z heart". The subject ("Pete") is treated in the same way as in the previous examples. The
argument substitution 1"ele substitutes the variable by the
NP "Pete", giving the structure in (44), in which, event-
tmlly, the NP "Mary" substitutes for the argument variable
x I. Special M-Rules will have to be added to an M-granmar
to achieve this kind of substitution. "Normal" argument
323
substitution rules substitute for the variables in their
canonical positions, i.e. as a subject or (indirect) object
directly under the clause node or as an object to a
preposition in a prepositional object.
(43) Pete broke Mary's heart
(44) CL
NP VERB NP
hJad "break" det/\head
I / \
NOUN VAR NOUN
"Pete" x I "heart"
The argument substitution rule for this type of construct
looks like the following:
Rlo,h: if t I is of category NP and
t 2 is of the form CL\[n~al,
NP\[det/VAR(~), mu2\], mu3\]
then: CL\[mul, NP\[de~/tl, mu2\], mu3\]
In this rule tl is assigned genitive case.
Rule R. 0 h applied to NP(Ymry) results in CL(Pete break
Mary's ~e'ar t).
In this way it is also possible to deal with the constructs
mentioned in the introduction, as for example "x\] ram x 2
down x3"s throat"~
4.2 Variables Bound hy Arguments
Sentence (45) contains a possessive
refers to the subject "the boy". In
expression is represented as in (46).
(45) the boy lost his te~nper
(46) VERB I
VAR VERB NP
V 1 "lose" /N
det head
/ \
POSSPRO NOUN
V I "t~nper"
The M-Rule that inserts the CBE makes all possible forms of
the possessive pronoun (his, her, their, etc.). The substi-
tution rule for the subject decides upon the form of the
possessive pronoun.
In (47) the possessive pronoun "her" is bound to the object
"the woman". The treatment here is similar to the one
above. The argument to which the pronoun has to be bound is
indicated in the lexicon.
(47) the man gave the woman her freedom
5 Conclusion
The method described in this paper for the treatment of
idioms can deal with the problems traditionally related to
expressions of this type. Structural transfer is not
necessary, since idioms are mapped onto basic meanings. The
grammar can operate on idiom structures in the same way as
it operates on non-idiomatic structures , whil@, in the case
of certain idioms, restrictions on operations are spec-
ified. A test implementation in the Rosetta machine trans-
lation system has shown that this approach is promising.
324
pronoun "his", that
the lexicon the basic
Acknowledgements
The author would like to thank all n~mbers of the Rosetta
team, particularly Jan Landsbergen and Jan Odijk, for their
helpful comments on earlier versions of this paper. This
work was supported in part by a grant from the Nederlandse
Her st ruc tur eringsmaat schappij (NEHEM).
Notes
(i) Different native speakers of a language may vary in
their judgements about the possible transformations an
idiom may undergo. 1hough this Doses a problem, it will be
ignored for the present.
(2) This paper deals only with idioms with a verb as head.
Idioms of the type "spic and spaN' and "at any rate" are
"fixed', i.e. they cannot undergo any syntactic trans-
formations. They are therefore less interesting from a
theoretical point of view. In Rosetta fixed idioms will be
treated as one word in the morphological component.
(3) Basic S-trees are similar to the Montague gralmmr
concept of basic expressions. The term basic expression
will be used frequently to indicate both~
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