File Information
File: 05-lr/acl_arc_1_sum/cleansed_text/xml_by_section/metho/91/p91-1025_metho.xml
Size: 28,037 bytes
Last Modified: 2025-10-06 14:12:47
<?xml version="1.0" standalone="yes"?> <Paper uid="P91-1025"> <Title>Resolving Translation Mismatches With Information Flow</Title> <Section position="5" start_page="193" end_page="194" type="metho"> <SectionTitle> EXAMPLE 2: FTP </SectionTitle> <Paragraph position="0"> ~Thls term was taken from Dorr (1990) where the problem of divergences in verb predicate-argument structures was treated. Our use of the term extends the notion to cover a much more general phenomenon.</Paragraph> <Paragraph position="1"> ENGLISH: 2. Type 'open', a space, and the name of the remote systems and press \[return\].</Paragraph> <Paragraph position="2"> The system displays system connection messages and prompts for a user name.</Paragraph> <Paragraph position="3"> 3. Type the user name for your account on the remote system and press \[return\].</Paragraph> <Paragraph position="4"> The system displays a message about passwords and prompts for a password if one is required. JAPANESE:</Paragraph> <Paragraph position="6"> 'open' kuuhaku rimooto sisutemu met wo taipu si \[RETURN\] 'open' space remote system name ACC type and \[RETURN\] slsntemn setnsokn messeesi to ynnsaa reel wo ton puronputo system connection message and user name ACC ash prompt ga hyousi s~reru NOM display PASSIVE rimooto slsutemu deno sihun no ak~unto no yuusa met remote system LOC SELF of account of user name wo t~ipu s |\[RETURN\] wo osu ACC type and \[RETURN\] ACC push pasuwaado ni ksnsurn messeess to, moshi pasuwaado Sa p~ssword about messaKe And, if password NOM hltuyon nara po~suwaado wo tou pronputo ga hyoujl sarern required then password ACC ask prompt NOM dlsplay PASSIVE The notable mismatches here are the definiteness and number of the noun phrases for &quot;space,&quot; &quot;user name,&quot; &quot;remote system,&quot; and &quot;name&quot; of the remote system in instruction step 2, and those for &quot;message,&quot; &quot;password,&quot; and &quot;user name&quot; in step 3. This information must be made explicit for each of these references in translating from Japanese into English whether or not it is decidable. It gets lost (at least on the surface) in the reverse direction.</Paragraph> <Paragraph position="7"> Two important consequences for translation follow from the existence of major mismatches between languages. First in translating a source language sentence, mismatches can force one to draw upon information not expressed in the sentence information only inferrable from its context at best.</Paragraph> <Paragraph position="8"> Secondly, mismatches may necessitate making information explicit which is only implicit in the source sentence or its context. For instance, the alternation of viewpoint between user and system in the FTP example is implicit in the English text, detectable only from the definiteness of noun phrases like &quot;a/the user name&quot; and &quot;a password,&quot; but Japanese grammar requires an explicit choice of the user's viewpoint to use the reflexive pronoun zibsn.</Paragraph> <Paragraph position="9"> When we analyze what we called translation divergences above more closely, it becomes clear that divergences are instances of lexical mismatches. In the blocks example above, for instance, there is a mismatch between the spatial relations expressed with English on, which implies contact, and Japanese ue, which implies nothing about contact. It so happens that the verb &quot;notteiru&quot; can naturally resolve the mismatch within the sentence by adding the information &quot;on top of&quot;. Divergences are thus lexical mismatches resolved within a sentence by coocurring lexemes. This is probably the preferred method of mismatch resolution, but it is not always possible. The mismatch problem is more dramatic when the linguistic resources of the target language offer no natural way to match up with the information content expressed in the source language, as in the above example of definiteness and number. This problem has not received adequate attention to our knowledge, and no general solutions have been proposed in the literature.</Paragraph> <Paragraph position="10"> Translation mismatches are thus a key translation problem that any MT system must face. What are the requirements for an MT system from this perspective? First, mismatches must be made recognizable. Second, the system must allow relevant information from the discourse context be drawn upon as needed. Third, it must allow implicit facts be made explicit as needed. Are there any systematic ways to resolve mismatches at all levels? What are the relevant parameters in the &quot;context&quot;? How can we control contextual parameters in the translation process? Two crucial factors in an MT system are then REPRESENTATION and REASONING. We will first describe our representation.</Paragraph> </Section> <Section position="6" start_page="194" end_page="194" type="metho"> <SectionTitle> 3 Representing the translation con- </SectionTitle> <Paragraph position="0"> tent and context Translation should preserve the information content of the source text. This information has at least three major sources: Content, Context, Language. From the content, we obtain a piece of information about the relevant world. From the context, we obtain discourse-specific and utterance-specific information such as information about the speaker, the addressee, and what is salient for them. From the linguistic forms (i.e., the particular words and structures), through shared cooperative strategies as well as linguistic conventions, we get information about how the speaker intends the utterance to he interpreted.</Paragraph> </Section> <Section position="7" start_page="194" end_page="195" type="metho"> <SectionTitle> DISTRIBUTIVE LATTICE OF INFONS. </SectionTitle> <Paragraph position="0"> In this approach, pieces of information, whether * they come from linguistic or non-linguistic sources, are represented as infons (Devlin 1990). For an n-place relation P, ((P, Zl, ...,z, ;1)) denotes the informational item, or infon, that zl, ..., xn stand in the relation P, and ((P, Zl,...,zn ;0)) denotes the infon that they do not stand in the relation. Given a situation s, and an infon or, s ~ ~ indicates that the infon a is made factual by the situation s, read s supports ~r .</Paragraph> <Paragraph position="1"> Infons are assumed to form a distributive lattice with least element 0, greatest element 1, set I of infons, and &quot;involves&quot; relation :~ satisfying: 3 for infons cr and r, if s ~ cr and cr ~ r then s ~ 1-This distributive lattice (I, =~), together with a nonempty set Sit of situations and a relation ~ on Sit x I constitute an infon algebra (see Barwise and Etchemendy 1990).</Paragraph> <Paragraph position="2"> THE LINGUISTIC INFON LATTICE. We propose to use infons to uniformly represent information that come from multiple &quot;levels&quot; of linguistic abstraction, e.g., morphology, syntax, semantics, and pragmatics. Linguistic knowledge as a whole then forms a distributive lattice of infons.</Paragraph> <Paragraph position="3"> For instance, the English words painting, drawing, and picture are associated with properties; call them P1, P2, and P3, respectively. In the following sublattice, a string in English (EN) or Japanese(JA) is linked to a property with the SIGNIFIES relation (written ==),4 and properties themselves are interlinked with the INVOLVES relation (=~): EN: &quot;picture&quot; ~-= Pl((picture, x; 1)) EN: &quot;painting&quot; == P2((painting, x; 1)) EN: &quot;drawing&quot; == P3((drawing, x; 1)) EN: &quot;oil painting&quot; =----- P4((oil painting, x; 1~ EN: &quot;water-color&quot; == Ph((water-color, x; 1))</Paragraph> <Paragraph position="5"> So far the use of lattice appears no different from familiar semantic networks. Two additional factors bring us to the basis for a general translation framework. One is multi-linguality. The knowledge of any new language can be added to the given lattice by inserting new infons in appropriate places and adding more instances of the &quot;signifies&quot; relations. The other factor is grammatical and discourse-functional notions. Infons can be formed from any theoretical notions whether universal or language-specific, and placed in the same lattice.</Paragraph> <Paragraph position="6"> Let us illustrate how the above &quot;picture&quot; sublattice for English would be extended to cover Japanese words for pictures. In Japanese, ~ (e) includes both paintings and drawings, but not photographs. It is thus more specific than picture but more general than painting or drawing. No Japanese words cosignify with painting or drawing, but more specific concepts have words-- ~ (aburae) for P4, (suisaiga) for P5, and the rarely used word ~ (senbyou) for artists' line drawings. Note that synonyms co- signify the same property. (See Figure 1 for the extended sublattice.) relation links the SIGNIFIER and SIGNIFIED to forrn a SIGN (de Saussure 1959). Our notation abbreviates standard infons, e.g., ((signifies, &quot;picture&quot;, EN, P1; 1)) .</Paragraph> <Paragraph position="8"/> <Paragraph position="10"/> <Paragraph position="12"> Lexical differences often involve more complex pragmatic notions. For instance, corresponding to the English verb give, Japanese has six basic verbs of giving, whose distinctions hinge on the speaker's perspectivity and honorificity. For &quot;X gave Y to Z&quot; with neutral honorificity, ageru has the viewpoint on X, and burets, the viewpoint on Z. Sasiageru honors Z with the viewpoint on X, and l~udasaru honors X with the viewpoint on Z, and so on. See As an example of grammatical notions in the lattice, take the syntactic features of noun phrases. English distinguishes six types according to the parameters of count/mass, number, and definiteness, whereas Japanese noun phrases make no such syntactic distinctions. See Figure 3. Grammatical notions often draw on complex contextual properties such as &quot;definiteness&quot;, whose precise definition is a research problem on its own.</Paragraph> </Section> <Section position="8" start_page="195" end_page="198" type="metho"> <SectionTitle> THE SITUATED UTTERANCE REPRE- </SectionTitle> <Paragraph position="0"> SENTATION. A translation should preserve as far as practical the information carried by the source text or discourse. Each utterance to be translated gives information about a situation being described-precisely what information depends on the context in which the utterance is embedded. We will utilize what we call a SITUATED UTTERANCE REPRESEN- null context of an utterance. 5 In translating, contextual information plays two key roles. One is to reduce the number of possible translations into the target language. The other is to support reasoning to deal with translation mismatches.</Paragraph> <Paragraph position="1"> the utterance is produced The content of each utterance in a discourse like the Blocks and FTP examples is that some situation is described as being of a certain type. This is the information that the utterance carries about the DESCRIBED SITUATION.</Paragraph> <Paragraph position="2"> The PHRASAL SITUATION represents the surface form of an utterance. The orthographic or phonetic, phonological, morphological, and syntactic aspects of an utterance are characterized here.</Paragraph> <Paragraph position="3"> The DISCOURSE SITUATION is expanded here in situation theory to characterize the dynamic aspect of discourse progression drawing on theories in computational discourse analysis. It captures the linguistically significant parameters in the current state of the on-going discourse, s and is especially useful for finding functionally equivalent referring expressions between the source and target languages. C/ * reference time = the time pivot of the linguistic SOur characterization of the context of utterance draws on a number of existing approaches to discourse representation and discourse processing, most notably those of Grosz and Sidner (1986), Discourse Representation Theory (Kamp 1981, Helm 1982), Situation Semantics (Barwise and Perry 1983, Gawron and Peters 1990), and Linguistic Discourse Model (Scha and Polanyi 1988).</Paragraph> <Paragraph position="4"> degLewis (1979) discussed a number of such parameters in a logical framework.</Paragraph> <Paragraph position="5"> 7Different forms of referring expressions (e.g. pronouns, demonstratives) and surface structures (i.e. syntactic and description (&quot;then&quot;) s * point of view = the individual from whose view-point a situation is described ~ * attentional state -- the entities currently in the focus and center of attention ~deg * discourse structural context = where the utterance is in the structure of the current discourse I z The specific UTTERANCE SITUATION contains information about those parameters whose values support indexical references and deixes: e.g., information about the speaker, hearer(s), the time and loca-tion of the utterance, the perceptually salient context, etc.</Paragraph> <Paragraph position="6"> The FTP example text above describes a situation in which a person is typing commands to a computer and it is displaying various things. Specifically, it describes the initial steps in copying a file from a remote system to a local system with ftp. Consider the first utterance in instruction step ~uttering, x, u, t; 1 ~ ^ ~addressing, ~, y, t; 1 Note that the parameter y of DeS for the user (to whom the discourse is addressed) has its value constrained in US; the same is true of the parameter t for utterance time. Similarly, the parameter r of DeS for the definite remote system under discussion is assigned a definite value only by virtue of the information in DiS that it is the unique remote system that is salient at this point in the discourse. This cross-referencing of parameters between types constitutes further support for combining all four situation types in a unified SUR. In order for the analysis and generation of an utterance to be associated with an SUIt, the grammar of a language should be a set of constraints on mappings among the values assigned to these parameters.</Paragraph> <Paragraph position="7"> 4 Translation as information flow 3 repeated here: Type the user name for your .... d , - ~ Translation must often be a matter of approxiaccoun~ on ~ne remo~e system an press Lre~urnj .......... It occurs in a type of DISCOURSE SITUATION where mating the meaning oI a source mnguage ~ex~ ramer than finding an exact counterpart in the target lanthere has previously been mention of a remote system and where a pattern has been established of alternating the point of view between the addressee and another agent (the local computer system). We enumerate below some of the information in the SUl~ associated with this utterance. The Described Situation (DES) of the utterance is</Paragraph> <Paragraph position="9"> Finally, the Utterance Situation (US) is phonetic) often carry equivalent discourse functions, so explicit discourse representation is needed in translating these forms. See also Tsujil (1988) for this point.</Paragraph> <Paragraph position="10"> s Reichenb~.h (1947) pointed out the significance of reference time, which in the FTP example accounts for why the addressee is to press \[return\] after typing the user name of his/her remote a~count.</Paragraph> <Paragraph position="11"> 9 Katagiri (to appear) describes how this parameter interacts with Japanese grammar to constrain use of the reflexive pronoun zibu~.</Paragraph> <Paragraph position="12"> 10 See Grosz (1977), Grosz et al. (1983), Kameyama (1986), Brennan et al. (1987) for discussions of this parameter.</Paragraph> <Paragraph position="13"> llThis parameter may be tied to the &quot;intentional&quot; aspect of discourse as proposed by Grosz and Sidner (1986). See, e.g., Scha and Polanyi (1988) and Hobbs (1990) for discourse structure models.</Paragraph> <Paragraph position="14"> guage since languages differ in the concepts and real-world entities for which they have words and grammatical constructs.</Paragraph> <Paragraph position="15"> In the cases where no translation with exactly the same meaning exists, translators seek a target language text that accurately describes the same real world situations as the source language text. 12 The situation described by a text normally includes additional facts besides those the text explicitly states. Human readers or listeners recognize these additional facts by knowing about constraints that hold in the real world, and by getting collateral information about a situation from the context in which a description is given of it. For a translation to be a good approximation to a source text, its &quot;fleshed out&quot; set of facts--the facts its sentences explicitly state plus the additional facts that these entail by known real-world constraints--should be a maximal subset of the &quot;fleshed out&quot; source text facts. Finding a translation with the desired property can be simplified by considering not sets of facts (infons) but infon lattices ordered by involvement relations including known real-world constraints. If a given infon is a fact holding in some situation, all infons in such a lattice higher than the given one (i.e., all further infons it involves) must also be facts in the situation. Thus a good translation can be found by looking for the lowest infons in the lattice that the source text either explicitly or implicitly requires to hold in the described situation, and finding a target language text that either explicitly or implicitly requires the maximal number 12In some special cases, translation requires mapping between different hut equivalent real world situations, e.g., cars drive on different sides of the street in Japan and in the US. of them to hold. 13 THE INFORMATION FLOW GRAPH. Translation can be viewed as a flow of information that results from the interaction between the grammatical constraints of the source language (SL) and those of the target language (TL). This process can be best modelled with information flow graphs (IFG) defined in Barwise and Etchemendy 1990. An IFG is a semantic formalization of valid reasoning, and is applicable to information that comes from a variety of sources, not only linguistic but also visual and other sensory input (see Barwise and Etchemendy 1990b). By modelling a treatment of translation mismatches with IFGs, we aim at a semantically correct definition that is open to various implementations. null IFGs represent five basic principles of information flow: Given Information present in the initial assumptions, i.e., an initial &quot;open case.&quot; Assume Given some open case, assume something extra, creating an open subcase of the given case.</Paragraph> <Paragraph position="16"> Subsume Disregard some open case if it is subsumed by other open cases, any situation that supports the infons of the subsumed case supports those of one of the subsuming cases.</Paragraph> <Paragraph position="17"> Merge Take the information common to a number of open cases, and call it a new open case.</Paragraph> <Paragraph position="18"> Recognize as Possible Given some open case, recognize it as representing a genuine possibility, provided the information present holds in some situation.</Paragraph> <Paragraph position="19"> RESOLVING MISMATCHES. First~ a translation mismatch is recognized when the generation of a TL string is impossible from a given set of infons. More specifically, given a Situated Utterance Representation (SUIt), when no phrasal situations of TL support SUR because no string of TL signifies infon a in SUR, The TL grammar cannot generate a string from SUR, and there is a TRANSLATION MISMATCH on 0 r.</Paragraph> <Paragraph position="20"> A translation mismatch on ~, above is resolved in one of two directions: Mismatch Resolution by Specification: Assume a specific case r such that r =:~ and there is a Phrasal Situation of TL that supports v. A new open case SUR' is then generated, adding r to SUR.</Paragraph> <Paragraph position="21"> 13As more sophisticated translation is required, We could make use of the multiple situation types to give more importance to some aspects of translation than others depending on the purpose of the text (see Hauenschild (1988) for such translaion needs).</Paragraph> <Paragraph position="22"> This is the case when the Japanese word ~ (e) is translated into either painting or drawing in English. The choice is constrained by what is known in the given context.</Paragraph> <Paragraph position="23"> Mismatch Resolution by Generalization: Assume a general case r such that a =~ r and there is a Phrasal Situation of TL that supports r. A new open case SUR' is then generated, adding 7- to SUR.</Paragraph> <Paragraph position="24"> This is the case when the Japanese word ~ (e) is translated into picture in English, or English words ppainting and drawing are both translated into (e) in Japanese. That is, two different utterances in English, I like this painting and I like this drawing, would both be translated into ~J~l'~ ~ Otl~ff ~'~ (watasi wa kono e ga suki desn) in Japanese according to this scheme.</Paragraph> <Paragraph position="25"> Resolution by generalization is ordinarily less constrained than resolution by specification, even though it can lose information. It should be blocked, however, when generalizing erases a key contrast from the content. For example, given an English utterance, I like Matisse's drawings better than paintings, the translation into Japanese should not generalize both drawings and paintings into ~ (e) since that would lose the point of this utterance completely.</Paragraph> <Paragraph position="26"> The mismatches must be resolved by specification in this case, resulting in, for instance, $J~1&quot;~'C/~&quot; 4 gO ~tt~e~A~ \]: 9 ~ ~t~ ~'t?'J&quot; ( watasi wa Matisse no abnrae ya snisaiga yorimo senbyou ga suki dest 0 'I like Matisse's line_drawings(P7) better than oil_paintings(P4) or water-colors(P5)'.</Paragraph> <Paragraph position="27"> There are IFGs for the two types of mismatch resolution. Using o for an open (unsubsumed) node and * for a subsumed node, we have the following: Both resolution methods add more infons to the given SUR by ASSUMPTION, but there is a difference. In resolution by specification, subsequent subsurnption does not always follow. That is, only by contradicting other given facts, can some or all of the newly assumed SUR's later be subsumed, and only by exhaustively generating all its subcases, the original SUR can be subsumed. In resolution by generalization, however, the newly assumed general case immediately subsumes the original SUR. 14 14Resolution by specification models a form of abductive inference, and generalization, a form of deductive inference THE TRANSLATION MODEL. Here is our characterization of a TRANSLATION: Given a SUR ( DeT, PS, DiS, US ) of the nth source text sentence and a discourse situation DiS&quot; characterizing the target language text following translation of the (n-1)st source sentence, find a SUR ( DeT', PS ~, DiS ~, US ~) allowed by the target language grammar such that DiS&quot; _C DiS ~ and ( DeT, PS, DiS, US ) ,~ ( DeT s, PS s, DiS ~, US'). (N is the approximates relation we have discussed, which constrains the flow of information in translation.) Our approach to translation combines SURs and IFGs (see Figure 4). Each SUR for a possible interpretation of the source utterance undergoes a FLOW OF TRANSLATION as follows: A set of infons is initially GIVEN in an SUR. It then grows by mismatch resolution processes that occur at multiple sites until a generation of a TL string is RECOGNIZED AS POSSIBLE. Each mismatch resolution involves AS-SUMING new SUR's and SUBSUMING inconsistent or superfluous SUR's. ~s Our focus here is the epistemologicai aspect of translation, but there is a heuristically desirable property as well. It is that the proposed mismatch resolution method uses only so much additional information as required to fill the particular distance between the given pair of linguistic systems. That is, the more similar two languages, leas computation. This basic model should be combined with various control strategies such as default reasoning in a sltuation-theoretic context. One way to implement these methods is in the abduction-based system proposed by Hobbs and Kameyama (1990).</Paragraph> <Paragraph position="28"> ~SA possible use of MERGE in this application is that two different SUit's may be merged when an identical TL string would be generated from them.</Paragraph> <Paragraph position="29"> in an actual implementation.</Paragraph> </Section> <Section position="9" start_page="198" end_page="198" type="metho"> <SectionTitle> 5 A translation example </SectionTitle> <Paragraph position="0"> We will now illustrate the proposed approach with a Japanese-to-English translation example: the first sentence of instruction step 3 in the FTP text.</Paragraph> <Paragraph position="1"> INPUT STRING: &quot;3. ~ -~'-- \]- &quot;:/.~ ~'J-~'C'~'J ~'ff)7&quot; ~/~=---~~&quot; 7&quot;L~ ~--y~9-o &quot; 1. In the initial SUR are infons for 9 -~-- b &quot;:I ~ ~&quot; (rimoofo sisutemu) 'remote system', 7' ~ :I i. (akaunfo) 'account', and :'---'~ (yu~zaa mei) 'user name'. All of thesewords signify properties that are signified by English COUNT nouns but the Japanese SUR lacks definiteness and number information.</Paragraph> <Paragraph position="2"> 2. Generation of English from the SUR fails because, among other things, English grammar requires NPs with COUNT head nouns to be of the type, Sg-Def, Sg-Indef, PI-Def, or Pl-Indef.</Paragraph> <Paragraph position="3"> (translation mismatch) 3. This mismatch cannot be resolved by generalization. It is resolved by assuming four sub-cases for each nominal, and subsuming those that are inconsistent with other given information. The &quot;remote system&quot; is a singular entity in focus, so it is Sg-Def, and the other three subcases are subsumed. The &quot;user name&quot; is an entity in center, so Definite. The &quot;account&quot; is Definite despite its first mention because its possesser (addressee) is definite. Both &quot;user name&quot; and &quot;account&quot; can be either Singular or Plural at this point. Let's assume that a form of default reasoning comes into play here and concludes that a user has only one user name and one account name in each computer.</Paragraph> <Paragraph position="4"> 4. The remaining open case permits generation of English noun phrases, so the translation of this utterance is done.</Paragraph> <Paragraph position="5"> OUTPUT STRING: &quot;Type the user name for your account on the remote system and ...&quot;</Paragraph> </Section> <Section position="10" start_page="198" end_page="199" type="metho"> <SectionTitle> 6 Conclusions </SectionTitle> <Paragraph position="0"> In order to achieve high-quality translation, we need a system that can reason about the context of utterances to solve the general problem of transla- null tion mismatches. We have proposed a translation framework based on Situation Theory that has this desired property. The situated utterance representation of the source string embodies the contextual information required for adequate mismatch resolution. The translation process has been modelled as a flow of information that responds to the needs of the target language grammar. Reasoning across and beyond the linguistic levels, this approach to translation respects and adapts to differences between languages.</Paragraph> </Section> class="xml-element"></Paper>