A Framework for Processing Partially Free Word Order* 
Hans Uszkoreit 
Artificial Intelligence Center 
SRI International 
333 Ravenswood Avenue 
Menlo Park, CA 94025 
Abstract 
The partially free word order in German belongs to the 
class of phenomena in natttral language that require a close in- 
teraction between syntax and pragmatics. Several competing 
principles, which are based on syntactic and on discourse in- 
formation, determine the \[ineac order of noun phrases. A solu- 
tion to problems of this sort is a prerequisite for high-quality 
language generation. The linguistic framework of Generalized 
Phrase Structure Grammar offers tools for dealing with-word 
order variation. Some slight modifications to the framework al- 
low for an analysis of the German data that incorporates just 
the right, degree of interaction between syntactic and pragmatic 
components and that can account for conflicting ordering state- 
ments. 
I. Introduction 
The relatively free order of major phrasal constituents in 
German belongs to the class of natural-language phenomena 
that require a closer interaction of syntax and pragmatics 
than is usually accounted for in formal linguistic frameworks. 
Computational linguists who pay attention to both syntax and 
pragmatics will find that analyses of such phenomena can provide 
valuable data for the design of systems that integrate these lin- 
guist ic components. 
German represents a good test case because the role of 
pragmatics in governing word order is much greater than in 
English while the role syntax plays is greater than in some of the 
so-called free-word-order languages like Warlpiri. The German 
data are well attested and thoroughly discussed in the descriptive 
literature The fact that English and German are closely related 
makes it easier to assess these data and to draw parallels. 
The .~imple analysis presented here for dealing with 
free word order in German syntax is based on the linguistic 
framework of Generalized Phrase Structure Grammar (GPSG}, 
especially on its Immediate Dominance/Linear Precedence for- 
malism {ID/LP), and complements an earlier treatment of 
German word order) The framework is slightly modified to ac- 
commodate the relevant class of word order regularities. 
The syntactic framework presented in this paper is not 
hound to any particular theory of discourse processing; it enables 
syntax to interact with whatever formal model of pragmatics one 
might want to implement. A brief discussion of the framework's 
implication~ for computational implementation centers Upon the 
problem of the status of metagrammatical devices. 
2. The Problem 
German word order is essentially fixed: however, there is 
some freedom in the ordering of major phrasal categories like 
NPs and adverbial phrases - for example, in the linear order of 
subject (SUB J), direct object (DOBJ), and indirect object (lOB J) 
with respect to one another. All six permutations of these three 
constituents are possible for sentences like (In). Two are given 
as {Ib) and (It). 
(la) Dann hatte der Doktor dem Mann die Pille gegeben. 
Then had the doctor the man the pill given 
(lb) Dann hatte dec Doktor die Pille dem Mann gegeben. 
Then had the doctor the pill the man given 
(It) Dann hatte die Pille der Doktor dem Mann gegeben. 
Then had the pill the doctor the man given 
All permutations have the same truth conditional meaning, 
which can be paraphrased in English as: Then the doctor gave 
the man the pill. 
There are several basic principles that influence the order- 
ing of the three major NPs: 
• The unmarked order is SUBJ-iOBJ-DOBJ 
• Comment (or focus) follows non-comments 
* Personal pronouns precede other NPs 
• Light constituents precede heavy constituents, 
*This rese.'trch was supported by the National Science Foundation Grant 
\[ST-RI03$50, The views and conclusions expressed in this paper are those 
,,r the :tutbor and should not be interpreted as representative of the views 
of the Nati.,nal Science Foundation or the United States government. I 
have benefited fr,~rn discussions with and comments from Barbara Grosz, 
Fernand,, Pcreira. Jane Robinson. and Stuart Shieber. 
tThe best overview of the current GPSG framework can be found in Gazdar 
and Pullum (1982). For :t description of the II)/LP format refer to Gazdar 
and Pullum (Ig8l} and Klein (1983), for the ID/LP treatment of German 
t,, tszkoreit (\]g82a. lgB2b} and Nerbonne (Ig82). 
t06 
The order in (la) is based on the unmarked order, (lb) would 
be appropriate in a discourse situation that makes the man the 
focus of the sentence, and (1c) is an acceptable sentence if both 
doctor and man are focussed upon. l use focus here in the sense of 
comment, the part of the sentence that contains new important 
information. (lc) could be uttered as an answer to someone 
who inquires about both the giver and recipient of the pill (for 
example, with the question: Who gave whom the pill?l. The 
most complete description of the ordering principles, especially of 
the conflict between the unmarked order and the topic-commeni, 
relation, can be found in Lenerz (1977). 
3. Implications for Processing Models 
Syntactic as well as pragmatic information is needed 
to determine the right word order; the unmarked-order prin- 
ciple is obviously a syntactic statement, whereas the topic- 
comment order principle requires access to discourse informa- 
tion. °, Sometimes different ordering principles make contradic- 
tory predictions. Example (lb) violates the unmarked-order 
principle; (In) is acceptable even if dem Mann \[the man\] is the 
focus of the sentence~ 3 
The interaction of ordering variability and pragmatics can 
be found in many languages and not only in so-called free-word- 
order languages. Consider the following two English sentences: 
(2a) I will talk to him after lunch about the offer. 
(2b) I will talk to him about the offer after lunch. 
Most semantic frameworks would assign the same truth- 
conditional meaning to (2a) and (2b), but there are discourse 
situations in which one is more appropriate than the other. (2a) 
can answer a que~-tion about the topic of a planned afternoon 
meeting, but is much less likely to occur after an order to men- 
tion the offer as soon as possible. 4 
Formal linguistic theories have traditionally assumed the 
existence of rather independent components for syntax, seman- 
tics, and pragmatics, s Linguistics not only could afford this 
idealization but has probably temporarily benefited from it. 
However, if the idealization is carried over to the computational 
implementation of a framework, it can have adverse effects on 
the efficiency of the resulting system. 
2The heaviness principle requires access to phonological information in ad- 
dition, but, :~ discussion of this dependence is beyond the scope of this 
paper. 
3Sentences that differ only in their discourse role assignments, e.g.. do not 
focus on the same constituent(s}, usually exhibit different sentential stress 
patterns. 
4The claim is not that these sentences are not interchangeable in the men- 
ti, .n~.d di.<o-,urse situations under any circumstances. In English. marked in- 
ton arian can usually overwrite default discourse role assignments associated 
w~.. the order of the constituents. 
$Scvera\[ more recent theories can account for the interaction among some of 
the components. Montague Grammar (Montague. 1974) and its successors 
(incl. GPSG) link semantic and syntactic rules. Work on presuppositions 
(Karttunen and Peters. 1979), discourse representations (Kamp, If80) and 
Situati~,n Semantics (Barwise and Perry. 1981) narrows the gap between 
.,,.'mantics and pragmatics. 
If we as.~ume that a language generation system should be 
able to generate all grammatical word orders and if we further 
assume that, every generated order should be appropriate to the 
given discourse situation, then a truly nonintegrated system, i.e., 
a system whose semantic, syntactic, and pragmatic components 
apply in sequence, has to be inel~cient. The syntax will first 
generate all possibilities, after which the pragmatic component 
will have to select the appropriate variant. To do so, this com- 
ponent will also need access to syntactic information. 
In an integrated model, much unnecessary work can be 
saved if the syntax refrains from using rules that introduce prag- 
matically inappropriate orders. A truly integrated model can 
discard improper parses very early during parsing, thereby con- 
siderably reducing the amount of syntactic processing. 
The question of integrating grammatical components is a 
linguistic problem. Any reasonable solution for an integration 
of syntax and pragmatics has to depend on linguistic findings 
about the interaction of syntactic and pragmatic phenomena. An 
integrated implementation of any theory that does not account 
for this interaction will either augment the theory or neglect the 
linguistic facts. 
By supporting integrated implementations, the framework 
and analysis to be proposed below fulfill an important condition 
for effcient treatment of partially free word order. 
4. The Framework and Syntactic Analysis 
4.1 Tile Framework of CPSG in ID/LP Format 
The theory of GPSG is based on the assumption that 
nat ural languages can be generated by context-free phrase struc- 
ture (CF-PS) grammars. As we know, such a grammar is bound 
to exhibit a high degree of redundancy and, consequently, is 
not the right formalism for encoding many of the linguistic 
generalizations a framework for natural language is expected 
to express. However. the presumption is that it is possible to 
give a condensed inductive definition of the CF-PS grammar, 
which contains various components for encoding the linguistic 
regt,laritics and which can be interpreted as a metagrammar, 
i.e.. a grammar for generating the actual CF-PS grammar. 
A GPSG can be defined as a two-leveJ grammar containing 
a metagrammar and an object grammar. The object grammar 
combines {CF-PS} syntax and model-theoretic semantics. Its 
rules are ordered triples (n. r. t) where n is an integer (the rule 
number}, r is a CF-PS rule. and t is the tramlationoft.he rule, its 
denotation represented in some version of intensional logic. The 
translation t is actually an operation that maps the translation 
of the children nodes into the translation of t.he parent. The 
nonterminals of r are complex symbols, subsets of a finite set 
of syntactic features or - as in the latest version of the theory 
(Gazd:w and Pullum, 1982) - feature trees of finite size. The 
rules o/' the obJect grammar are interpreted as tree-admissability 
conditions. 
The metagrammar consists of four different kinds of rules 
that are used by three major components to generate the object 
107 
grammar in a stepwise fashion. Figure {3) illustrates the basic 
structure of a GPSG metagrammar. 
(3) 
{Basic Rules ~N~ IDR doubles)j/ 
Application~ \[ Metarule 
(IDR doubles) 
Rule Extension I 
i 
IDR triples) 
I binearization .' 
l 
~{bjeet-G rammar~'X~ F-PS Rules),~/ 
Metaxules ) 
~Rule Ext. Princpls). 
LP rules ) 
First. there is a set of banjo rules. Basic rules are immediate 
domi.a.ce rule (IDR) double~, ordered pairs < n,i >, where n 
is the rule number and i is an \[DR. 
1DRs closely resemble CF-PS rules, but, whereas the CF- 
PS rule "1 -- 6t 6..... 6. contains information about both 
immediate dominance and linear precedence in the subtree to be 
accepted, the corresponding IDR "~ -- 6t, /f~. ..... /f. encodes 
only information about immediate dominance. The order of 
the right-hand-side symbols, which are separated in IDRs by 
commas, has no significance. 
Metarule Application, maps \[DR doubles to other IDR 
doubles. For this purpose, metaxules, which are the second kind 
of rules are applied to basic rules and then to the output of 
metarule applications to generate more IDR doubles. Metarules 
are relations between sets of IDRs and are written as A = B, 
where A and B are rule templates. The metarute can be read as: 
If there is an IDR double of kind A, then there is also an IDR 
double of kind /3. In each case the rule number is copied from A 
to /3. s 
.Several metarules can apply in the derivation of a single 
II)R double; however, the principle of Finite Closure, defined 
by Thompson (1982}, allows every metarule to apply only once 
in the derivational history of each IDR double. The invocation 
of this principle avoids the derivation of infinite rule sets, in- 
6Rule number might he a misleading term for n because this copying :~.ssigns 
the s~me integer to the whole class of rules that were derived from the 
~ame basic rules. This rule number propagation is a prerequisite for the 
<iPSG accouht of subcategori2ation. 
eluding those that generate non-CF, non-CS, and noarecursive 
languagesJ 7 
Another component maps IDR doubles to IDR triples, 
which are ordered triples (n,i,t) of a rule number., an IDR i, 
and a translation t. The symbols of the resulting IDRs axe fully 
instantiated feature sets (or structures} and therefore identical to 
object grammar symbols. Thus, this component adds semantic 
translations and instantiates syntactic features. The mapping is 
controlled by a third set of rule czten6io, principles including 
feature co-occurrence restrictions, feature def. ult principles, and 
an algorithm that assigns the right kind of translation to each 
rule on the basis of its syntactic information. 
The last component of the metagrammar maps the IDR 
triples to the rules of the object grammar. For each IDR triple 
all the object grammar triples are generated whose CF-PS rules 
conform with the linear precedence(LP) rules, the fourth rule set 
of the metagrammar. LP rules are members of the LP relation, 
a partial ordering on V'r I.I VN. An LP rule (a,$} is usually 
written as a < ~/and simply states that a precedes/9 whenever 
both a and d occur in the right-hand-side of the same CF-PS 
rule. 
It is the separation of linear precedence from immediate 
dominance statements in the metagrammar that is referred to 
.as ID/LP format. And it is precisely this aspect of the for- 
malism that. makes the theory attractive for application to lan- 
guages with a high degree of word-urder freedom. The analysis 
presented in the next section demonstrates the functioning of the 
formalism and some of its virtues. 
4.2 The Analysis of German Word Order 
Uszkoreit (1982a) proposes a GPSG analysis of German 
word order that accounts for the fixed-order phenomena, includ- 
ing the notoriously difqcult problem of the position of finite and 
nonfinite verbs. Within the scope of this paper it is impossible to 
repeat, the whole set of suggested rules. A tiny fragment should 
sumce to demonstrate the basic ideas as well as the need for 
modifications of the framework. 
Rule (41 is the basic VP ID rule that combines ditransitive 
verbs like forms of gebe. (give) with its two objects: 
(4} (,5, VP -- .NP, NP, V) 
\[+DATI\[+ACC\] 
Th,~ rule .~tates that a VP can expand as a dative NP (IOBJ}, 
an attn.-alive NP (DOBJ), and a verb. Verbs that can occur 
in dilrnnsitive VPs, like geben (give). are marked in the lexicon 
with the rule number 5. Nothing has been said about the linear 
order of these constituents. The following metarule supplies a 
"flat" sentence rule for each main verb VP rule \[+NOM 1 stands 
for the nominative case, which marks the subject. 
7F, r ~ d*scu.-sion see Peters and Uszkoreit (1982} and Shieber et M. (1983}. 
I08 
(5) VP ~ X, V ~ S -.* NP, X, V 
\[-AUX\] \[+NOM\] 
It generates the rule under (6) from (4): 
(6) (5, S ---, NP, NP, NP, V) 
\[+ NOMI\[+DAT\]\[+ACC\] 
Example (7) gives a German constituent that will be admitted 
by a PS rule derived from ID rule (6): 
(7} der Doktor dem Mann die Pille gegeben 
the doctor the man the pill given 
I shall not list the rules here that combine the auxiliary halle 
and the temporal adverb dann with (7) to arrive at sentence (la), 
since these rules play no role in the ordering of the three noun 
phrases. What is of interest here is the mapping from ID rule (5) 
to t.he appropriate set of PS rules. Which LP rules are needed 
to allow for all and only the acceptable linearizations? 
The position of the verb is a relatively easy matter: if 
it is the finite matrix verb it precedes the noun phrases; in all 
other cases, it follows everything else. We have a feature MC 
for matrix clause as well as a feature co-occurrence restriction to 
ensure that +MC will always imply +FIN (finite). Two LP rules 
are needed for the main verb: 
(Sa) +MC < NP 
(8b) NP <-MC 
The regularities that govern the order of the noun phrases can 
also be encoded in LP rules, as in (ga)-!ge): 
(Oa) +NOMINATIVE < +DATIVE 
(9b) +NOMINATIVE < +ACCUSATIVE 
(9c) +DATIVE < +ACCUSATIVE 
(9d) -FOCUS < +FOCUS 
(9e) +PRONOUN < -PRONOUN 
(Kart.tunen and Peters, 1979) 8 or a function from discourse situa- 
tions to the appropriate truth-conditional meaning in the spirit 
of Barwise and Perry (1981). The analysis here is not concerned 
with choosing a formalism for an extended semantic component, 
but rather with demonstrating where the syntax has to provide 
for those elements of discourse information that influence the 
syntactic structure directly. 
Note, that the new LP rules do not resolve the problem 
of ordering-principle conflicts, for the violation of one LP rule is 
enough to rule out an ordering. On the other hand, the absence 
of these LP rules would incorrectly predict that all permutations 
are acceptable. The next section introduces a redefinition of LP 
rules that provides a remedy for this deficiency. 
4.3 The Modified Framework 
Before introducing a new definition of LP rules, let me 
suggest, anot.her modification that will simplify things somewhat. 
The I,P rules considered so far are not really LP rules in the sense 
in which they were defined by their originators. After all. LP 
rules are defined as members of a partial ordering on "v~,¢ U VT'. 
Our rules are schemata for LP rules at best, abbreviating the 
huge set of UP rules that are instantiations of these schemata. 
This definition is an unfortunate one in several respects. It 
not. only creates an unnecessarily large set of rules IVN con- 
tains thousands of fully instantiated complex symbols) but also 
suppresses some of the important generalizations about the lan- 
guage. Clearly, one could extract the relevant generalizations 
even from a fully expanded LP relation, e.g., realize that there is 
no LP rule whose first element has -MC and its second element 
NP. However, it should not be necessary to extract generaliza- 
tions from the grammar; the grammar should express these 
generalizat.ions directly. Another disadvantage follows from the 
choice of a procedure for arriving at the fully expanded LP rela- 
Lion. Should all extensions that are compatible instantiations 
of (Sa), (Sb). and (9a)-(9e} be LP rules: If so. then (10) is an 
instantiat.ion of (8a): 
(I0) +MC' NP 
+DEF < +FIN 
,.\ feature FOCUS has been added that designates a focused con- 
sf it,eat. Despite its name FOCUS is a syntactic'fcature, justified 
by syntactic Pacts, such as its influence on word order. This 
syntactic feature needs t,o be linked with the appropriate dis- 
course information. The place to do this is in the rule exteu- 
sioq component, where features are instantiated and semantic 
translations added to ID rules. It is assumed that in so doing 
the translation part of rules will have to be extended anyway so 
as to incorporate non-truth-conditional aspects of the meaning. 
For example, the full translation could be an ordered pair of 
truth-conditional and non-truth-conditional content, extending 
Karttunen and Peters's treatment of conventional implicature 
Yet nothing can be a matrix verb and definite simultaneously, 
and NPs cannot be finite. (101 is a vacuous rule. Whether 
il is a LP rule at all will depend on the way the nonterminal 
vocabulary of the object grammar is defined. If it only includes 
the nonterminals that actually occur in rules then (10) is not 
as LP rule. \[n this case we would need a component of the 
metagrammar, the feature instantiation principles, to determine 
8T,~ be more precise. Karttunen and Peters actuaJly make their transla- 
ti,,ns ordered triples of truth-conditiona.l content, impllcatures, and an in- 
hcrhance expression that plays a role in h~.ndling the projection problem 
for presuppositions. 
109 
another compouent of the metagrammar, the LP component. 9 
LP will be redefined as a partial order on 2 p, where F is the set 
of syntactic features I0 
The second and more important change can best be 
described by viewing the LP component as a function from a pair 
of symbols (which can be characterized as feature sets) to truth 
values, telling us for every pair of symbols whether the first can 
precede the second in a linearized ru!e. Given the LP relation 
{(al,~/t),(a~,B~.) ..... (a~,~)} and a pair of complex symbols 
(3',6), the function can be expressed as in (11). 
(11} cl A c,~ A ... A c,~ where 
c~ ---- ~(~; _C 6 A #; C: 3') 
for 1 < i < n 
~,Ve call the conjunct clauses LP conditions; the whole con- 
junction is a complex LP condition. The complex LP condi- 
tion allows "T to precede /~ on the right-hand side of a CF- 
PS rule if every LP condition is true. An LP condition ct 
derived from the LP rule (a~,//i) is true if it is not the case 
that 3 has the features ;/~ and 6 has the features a¢. Thus 
the LP rule NP < VP stanch for the following member 
of the LP relation {{+N,-V, +2B~R}, l-N, +V, +2BAR}). 
The LP condition following from this rule prevents a su- 
perset of {-N, +V, +2BAR} from preceding a superset of 
l-N, +V, +2BAR}, i.e., a VP from preceding an NP. 
But notice that there is nothing to prevent us from writing 
a fictitious LP rule such as 
(12} +PRONOUN < -ACCUSATIVE 
German has verbs like Ichrcn that take two accusative noun 
phr~.ses as complements. If {12) were an LP rule then the result- 
ing LP condition defined as in ( l 1 ) would rule out any occurrence 
of two prouominalized sister NPs because either order would be 
rejected.l 1 
It. is an empirical question if one might ever find it useful 
to write LP rules as in (12}, i.e., rules a < ~/, where a U 3 
could be a ~ubset of a complex symbol. Let me introduce a 
minor redefinition of the interpretation of LP, which will take 
care of cases such as (12) and at the same prepare the way for 
a more substantial modification of LP rules. LP shall again be 
interpreted as a function from pairs of feature sets (associated 
with complex symbols} to truth values. Given the LP relation 
{(a1,,'Jl),(oo..;\]'.,} ..... (a.,~q~) and a pair of complex symbols 
0The widety uscd notation for nomnstantiated LP rules and the feature in- 
stantiati,,n principles could be regarded an meta, met.Lgrammatical devices 
that inductively define a part of"the metagrammar. 
10Remember that, in an .~-synta.x. syntactic categories abbreviate feature 
sets NP ~ {+N, -V, +2BAR}. The definition can emily be extended 
to work on feature trees instead of feature sets. 
1 lln principle, there is nothing in the original ID/LP definition either that 
would prevent the grammar writer from abbreviating a set of LP rules by 
(121. It is not quite clear, however, which set of LP rules is abbreviated 
by (r"). 
(3',/~), the function can be expressed as in (13). 
(13) ct A c2, A ... A cn where 
~, - (a~c6 A B~C3,)-(o~C3, A B, C6) 
for l < i < n 
That means 3' can precede 6 if all LP conditions are true. 
For instance, the LP condition of LP rule (12) will yield false 
only if "t is +ACCUSATIVE and # is +PRONOUN, and either 
3, is -PRONOUN or 6 is -ACCUSATIVE (or both). 
- Now let. us assume that, in addition to the kind of simple 
LP rules just introduced, we can also have complex LP rules con- 
sisting of several simple LP rules and notated in curled brackets 
a.s in (14}: 
{14) '+NOMINATIVE < +DATIVE \] 
+NOMINATIVE < +ACCUSATIVE| 
+DATIVE < +ACCUSATIVE~ 
-FOCUS < +FOCUS | 
+PRONOUN < -PRONOUN / 
The LP condition associated with such a complex LP rule 
shall be the disjunction of the LP conditions assigned to its 
members. LP rules can be generally defined as sets of ordered 
pairs of feature sets {(at,Bt),(a~,~) ..... (am,~/m)}, which are 
either notated with curled brackets as in (10), or, in the case of 
singletons, as LP rules of the familiar kind. A complex LP rule 
{{at, dl), (no_, ,%) ..... {am, B,n)} is interpreted as a LP condition 
of the following form {(o 1 C 6 A~t C -~)V(a~ C 6 At/= C_ 
-,)v . vt~.,C6A~,,C_~))--((a, C_3,A3, c_ ~}v(a.. c_ 
"l A ,'t= C 6)V ... V(am C 3, A dm ~ 6)}. Any of the atomic LP 
rules within the complex LP rule can be violated as long as the 
violations are sanctioned by at least one of the atomic LP rules. 
Notice that with respect to this definition, "regular" LP 
rules, i.e., sing{elons, can be regarded as a speciaJ case of complex 
I,P rules. 
\[ want ¢o suggest that the LP rules in {Sa}, (8h), and (l-I} 
arc a subset of the LP rules of German. This analysis makes a 
number of empirical predictions. For example, it predicts that 
(15) and (16) are grammatical, but not (17). 
(15) Dann batte der Doktor dem Mann die Pille gegeben 
-FOCUS +FOCUS -FOCUS 
+NOM +DAT +ACC 
Then had the doctor the man the pill given 
(18) Dana hatte der Doktor die Pille dem Mann gegeben 
-FOCUS +FOCUS +FOCUS 
+NOM - +ACC +DAT 
Then had the doctor the pill the man given 
(17)??Dann hatte der Doktor die Pille dem Mann gegeben 
-FOCUS +FOCUS -FOCUS 
+NOM +ACC +DAT 
Then had the doctor the pill the man given 
ii0 
In (17) the sub-LP-rules +DAT < +ACC and -FOCUS < 
+FOCUS are violated. No other sub-LP-rule legitimizes these 
violations and therefore the sentence is bad. 
This agrees with the findings of Lenerz (1977), who tested 
a large number of sample sentences in order to determine the 
interaction of the unmarked syntactic order and the ordering 
preferences introduced by discourse roles. There are too many 
possible feature iustantiatious and permutations of the three 
noun phrases to permit making grammaticality predictions here 
for a larger sample of ordering variants. So far 1 have not 
discovered any empirical deficiencies in the proposed analysis. 
5. Implications for Implementations 
The theory of GPSG, a,s described by its creators and as 
outlined in this paper, cannot be used directly for implementa- 
tion. The number of rules generated by the metagrammar is just 
too large. The Hewlett-Packard system (Gawron etal., 1982} as 
well as Henry Thompson's program, which are both based on a 
pre-ID/LP version of GPSG, use metarules as metagrammatical 
devices, but with feature iustantiation built into the processor. 
Agreement checks, however, which correspond to the work of 
the metagrammatical feature instantiation principles, are done 
at parse time. As Berwick and Weinberg (1982\] have pointed 
out, the cont ext-freeness of a grammar might not accomplish 
much when the number of rules explodes. The more components 
of the metagrammar that can be built into the processor (or 
used by it as additional rule sets at parse time), the smaller the 
resulting grammar will be. The task is to search for parsing 
algorithms that. incorporate the work of the metagrammar into 
context-free phrase structure parsing without completely losing 
the parsing time advantages of the latter. Most PSG parsers do 
feature handling at parse time. Recently, Shieber (forthcoming) 
has extended the Earley algorithm (Earley 1970) to incorporate 
the linearization process without a concomitant loss in parsing 
c~ciency. The redefinition of the LP component proposed in 
this paper can be intrusted easily and efficiently into Shieber's 
extension. 
If the parser uses the disjunctive LP rules to accept all or- 
dering variants that are well-formed with respect to a discourse, 
there still remains the question of how the generator chooses 
among the disjuncts in the LP rule. It would be very surprising 
if the different orderings that can be obtained by choosing one 
LP rule disjua:t over another did in fact occur with equal fre- 
quency. Although there are no clear results that might provide 
an answer to this question, there are indications that certain dis- 
juntas "win out" more often than others. However, this choice 
is purely stylistic. A system that is supposed to produce high- 
quality output might contain a stylistic selection mechanism that 
avoids repe, hions or choose~ among variants according to the 
tyt:e of text or dialogue. 
6. Conclusion 
The proposed analysis of partially free word order in 
German makes the accurate predictions about the gram- 
musicality of ordering variants, including their appropriate- 
ness with respect to a given diseo~se. The 1D/LP format, 
which has the mechanisms to handle free word order, has been 
extended to account for the interaction of syntax and prag- 
mat.its, as well as for the mutually competing ordering principles. 
The modifications are compatible with efficient implementation 
models. The redefined LP component can be used for the im- 
plementation of stylistic choice. 
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