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We provide an extended discussion of analyses of relative clauses (prototypically clauses with a noun modifying function) and related constructions that have appeared in the HPSG literature. The basic theoretical approaches are presented (specifically, the lexical “head-driven” approach associated with earlier work in HPSG and the more recent constructional approach), followed by descriptions of analyses of different kinds of relative clause across a range of typologically diverse languages (notably Arabic, English, French, German, Japanese, and Korean). Phenomena discussed include wh-relatives, relatives headed by complementisers, “bare” relatives, non-restrictive relatives, extraposition of relative clauses, relative clause-like constructions that function as complements, various kinds of “dependent noun” and “pseudo” relative clause, and free (headless) relatives. &nbsp

With the advent of a new Precision Time Protocol specification, new opportunities abound for clock synchronization possibilities within power grid control systems. The third iteration of the Institute of Electrical and Electronics Engineers Standard 1588 specification provides several new features specifically aimed at complex, wide-area deployments in which situational awareness and control require precise time agreement. This paper describes the challenges faced by existing technology, introduces the new time distribution specification, and provides examples to explain how it represents a game-changing innovation.

Modern Standard Arabic (MSA) has simple and complex comparatives, which look rather like their counterparts in many other languages. MSA simple comparatives are indeed like those of other languages, but MSA complex comparatives are quite different. They involve an adjective with a nominal complement, which may be an adjectival noun or an ordinary noun, and are rather like so-called ˋadjectival constructs'. Simple comparatives, complex comparatives, and adjectival constructs can all be analysed with lexical rules within HPSG.

According to a ‘radical orphanage’ approach, non-restrictive relative clauses are not part of the syntactic representation of the sentence that contains them. It is an appealing view, and seems to capture some important properties of non-restrictive relative clauses. Focusing mainly on empirical shortcomings, this paper aims to show that the appeal of such approaches is illusory. It also outlines an empirically superior ‘syntactically integrated’ account.

This paper addresses the issue of phonologically null elements in HPSG by providing an analysis of the construction exemplified by NPs such as ˋthe rich', ˋthe beautiful', ˋthe unemployed', which lack an overt noun. The properties of this construction are explored in detail, and a number of approaches described: in particular approaches which posit a phonologically empty noun, and constructional approaches. It is shown that a constructional approach is empirically superior. This is interesting, theoretically, because empirical differences between such approaches have proved elusive hitherto.

There have been important developments in computationally oriented linguistic theory in the last 10 years, in particular, the development of formalisms based on UNIFICATION. This is already important as regards Machine Translation research, and will become increasingly so as the next generation of practical MT systems evolves. One purpose of this paper is tutorial — to give an overview of these developments, to say why they are positive and to explore their application in the context of MT. The paper also has a non-tutorial aim of conceptual clarification: we think these developments contain a number of options that are interestingly different., D'importants développements se sont produits ces dix dernières années en linguistique informatique, plus particulièrement dans le cas des formalismes basés sur l'UNIFICATION. Ce formalisme est déjà important dans la recherche en traduction automatique et il le sera de plus en plus au fur et à mesure que de nouveaux systèmes de TA verront le jour. Un des buts du présent article est pédagogique : il s'agit de présenter les nouveaux développements en matière de linguistique informatique, de faire valoir les aspects positifs et d'expliquer leur applicabilité dans le contexte de la TA.

So-called ˋˋExhaustive Conditionals'' (ECs, also known as ˋˋUnconditionals'') have been an important focus of recent research. We develop an HPSG analysis of governed ECs (e.g. ˋno matter how intelligent the students are ...'), sketch an approach to ungoverned ECs (e.g. ˋhowever intelligent the students are...'), and evaluate three possible analyses of reduced ECs (e.g. ˋno matter how intelligent the students ...', ˋhowever intelligent the students...').

This paper introduces the topic of evaluation of natural language processing systems, and discusses the role of test suites in the linguistic evaluation of a system. The work on test suites that is being carried out within the framework of the TSNLP project is described in detail and the relevance of the project to the evaluation of machine translation systems considered.

To begin with, I would like to welcome the idea of having 'forum' style peer group commentary of papers in MT: one of the less appealing features of the field is the general lack of communication between people who work on different projects, or with different assumptions. Apart from being unappealing, it also damaging to the field, since one effect is that people rarely learn about, and so cannot learn from, each other's mistakes (or successes). It may be that this forum will go some way to change things by encouraging debate. In this context, of course, Harry Somers' (HLS) stimulating paper is a good starting point, because, despite having concentrated mainly on work in some way connected with his own institution in the fourth section ('Some Alternative Avenues of Research), he has given, in the earlier sections, what seems to me a very reasonable summary of what is, and has been, going on. However, I have some fundamental disagreements with the paper. The first is with the perspective that HLS takes in his critique of the 'second generation' . I think HLS assumes that MT is about the construction of working, commercial translation systems. It is with respect to this aim that he finds the second generation a failure. Now, while this is an important aim of MT research, it not the only aim. More generally, the main aim of MT research should be to enhance understanding about what is involved in automating the translation process. This involves (i) addressing issues, and (ii) developing techniques. (It is because of a failure to see this that so many conference papers on MT consist of pictures of outline boxes with arrows going between them, and unrevealing captions). I also think MT research may eventually have something to say about the nature of translation. This is an important goal that goes well beyond, and may be in tension with the practical goal of building MT systems. In a sense this perspective is a puzzling one for HLS to take (e.g. he does not continue with it when he talks in section 4 about avenues of research this is all about techniques), but for whatever reason, I think it leads him wrong in his evaluation of a number of things. One example

The primary aim of this contribution is to provide an editorial introduction to this Special Issue ofMachine Translation dedicated to Evaluation. The intention is to describe the rationale for the Issue, outline the various contributions of the papers in this issue, and try to situate them in a wider context. As part of providing this wider context, we give an overview and assessment of the main current approaches to Evaluation of Natural Language Processing, and especially Machine Translation systems.

Non-restrictive relative clauses (NRRCs) can modify constituents which undergo ˋpragmatic enrichment' when they appear in answers to questions. For example, in an interchange like: ˋA: What did Jo think? B: That you should say nothing, which is surprising.' What B says is surprising is that ˋJo thinks ...' On the face of it, this might seem problematic for approaches to NRRCs which assume ˋsyntactic integration' and to support an ˋorphan' analysis, where NRRCs are combined with purely conceptual representations. In this paper we examine a range of elliptical and anaphoric phenomena, and show that this conclusion is misplaced. In fact, the phenomena argue strongly in favour of a syntactically integrated analysis.

The purpose of this paper is to describe and motivate the leading ideas behind the MiMo notation, a formalism for transfer-based machine translation which is especially appropriate for intermediate representations based on Dependency Grammar. The most important of these ideas concern properties of the translation relation such as compositionality, reversibility, modularity, and autonomy of levels of description. The final section considers some issues relating to rule interaction.

This paper discusses the NP-internal agreement strategies observed in an empirical (corpus based) study of Portuguese, and proposes an analysis which is formalized in the framework of Head-Driven Phrase Structure Grammar (HPSG). The empirical study suggests that what were previously thought to be rare or non-existent strategies occur with surprising frequency. Capturing these strategies poses problems for many standard approaches to agreement. The formalization shows how they can be captured with a relatively conservative extension of the existing HPSG theory of agreement.

This paper presents an account of English non-restrictive (ˋappositive') relative clauses (NRCs) in the framework of ˋconstruction based' HPSG. Specifically, it shows how the account of restrictive relative clause constructions presented in Sag (1997) can be extended to provide an account of the syntax and semantics of NRCs and of the main differences between NRCs and restrictive relatives. The analysis reconciles the semantic intuition that NRCs behave like independent clauses with their subordinate syntax. A significant point is that, in contrast with many other approaches, it employs only existing, independently motivated theoretical apparatus, and requires absolutely no new structures, features, or types.

In this day an age, some corpus linguistics should be part of every course to do with language. But learning about corpus linguistics -- its possibilities and limitations --- is not just a matter of acquiring information. The best way to learn about corpus linguistics is to do it, and the best way to teach corpus linguistics is to put students into a position where they can do it ((Leech, 1997), (Fligelstone, 1993)). This requires corpora, and tools, in addition to teaching materials.

The normal method for representing anaphoric dependencies in Unification Based grammar formalisms is that of re-entrance. In this paper, we address the problems that this representational device poses when such formalisms are used for translation. We demonstrate the inadequacies of existing proposals, and describe an approach which exploits the expressive possibilities of the equational constraint language in LFG and involves an inferential procedure combining underspecification in the statement of bilingual correspondences with the use of target language knowledge.

Flavonoid aglycone variation within Helianthus annuus, a species widely distributed throughout North America, was analyzed. Flavonoid aglycones of H. annuus consist of two types, flavones and chalcones. The flavone aglycones are sequestered in glandular trichomes that occur on both leaf surfaces, whereas the chalcone aglycones appear to be incorporated in the waxy leaf cuticle. Considerable variation in flavonoid profile was observed with some plants exhibiting as few as one, and others as many as seven of the eight aglycones detected. No definable phytogeographic patterns were observed for this flavonoid variation. Flavonoid aglycone variation also did not differentiate the infraspecific taxa within H. annuus. DURING THE PAST three decades, numerous studies have utilized interspecific flavonoid variation to assess phylogenetic relationships among species. In contrast, comparatively little effort has been made to document the extent of flavonoid variation within species or populations or to examine evolutionary problems existing at the intraspecific or population level (Harborne and Turner, 1984). Even fewer studies have determined the localization of the observed flavonoids in cells and tissues. Given the magnitude of adaptive functions ascribed to flavonoids (Thompson et al., 1972; McClure, 1975; Flint and Caldwell, 1983), flavonoid localization and infraspecific patterns of flavonoid variation may provide unique insights into the evolution of a species. Flavonoid studies in Helianthus have demonstrated the presence of four types of compounds: flavone and chalcone aglycones which appear to occur in external structures on the surface of leaves and flavonol glycosides and anthochlors that are present in leaf and floral tissue (Gershenzon, Mabry and Kreitner, 1981; Schilling and Mabry, 1981; Schilling, 1983). Because leaf flavonoid aglycones appear to occur externally, and can be easily and rapidly surveyed, we analyzed variation and localization of these compounds in H. annuus. ' Received for publication 3 April 1986; revision accepted 14 July 1986. We thank Drs. 0. Solbrig, A. J. Gilmartin, T. Duncan, B. Tumer and C. Heiser for permission to sample Helianthus leaves from herbarium specimens. Secial thanks to Ed Schilling for providing authentic compounds and for assistance in flavonoid identification, and to Jerry McClure for helpful comments on the manuscript. Support from an NSF dissertation im-provement'grant to LHR and DES, Sigma Xi award, Washington State Univ. travel award to LHR, and NSF grant BSR 8315098 to DES is gratefully acknowledged. Helianthus annuus L., an obligately outcrossing, annual sunflower, occurs throughout most of North America and comprises three subspecies, annuus, lenticularis, texanus, and one variety, macrocarpus. These taxa are distinguished primarily by length and width of the achenes, involucral bracts, discs, and ray flowers (Heiser, 1954). The ranges of the three subspecies are broadly overlapping; ssp. annuus occurs throughout the central and eastern U.S.; ssp. lenticularis occurs throughout western North America; ssp. texanus occurs in eastern Texas. Helianthus annuus var. macrocarpus is the cultivated sunflower. There is frequent intergradation between these taxa, often making delimitation difficult. In addition, frequent interand intraspecific hybridization further complicates the systematics of H. annuus (Heiser, 1954). We analyzed flavonoid aglycone profiles of numerous H. annuus specimens representing all three subspecies to: 1) aid in the delimitation of infraspecific taxa within this species, 2) determine whether any correlation exists between flavonoid profile variation and geographic location, and 3) determine the structure and localization ofthe flavonoid aglycones present in this species. MATERLIL AND METHODS-Two hundred and sixty-five individuals from throughout the range of H. annuus were analyzed for flavonoid aglycone variation, including 169 individuals of ssp. lenticularis, 46 individuals of ssp. texanus, 23 individuals of ssp. annuus, and 27 individuals morphologically intermediate between ssp. annuus and ssp. lenticularis. Leaf material utilized in this study was obtained from three sources: 1) field collections, 2) plants grown from seed under uniform conditions in

In this paper we provide an abstract characterisation of different kinds of robust processing in Machine Translation and Natural Language Processing systems in terms of the kinds of problem they are supposed to solve. We focus on one problem which is typically exacerbated by robust processing, and for which we know of no existing solutions. We discuss two possible approaches to this, emphasising the need to correct or repair processing malfunctions.

In this paper we address the problem of choosing the best solution(s) from a set of interpretations of the same object (in our case a segment of text). A notion of preference is stated, based on pairwise comparisons of complete interpretations in order to obtain a partial order among the competing interpretations. An experimental implementation is described, which uses Prolog-like preference statements.

This paper describes a model for MT, developed within the Eurotra MT project, based on the idea of compositional translation , by describing a basic, experimental notation which embodies the idea. The introduction provides background, section 1 introduces the basic ideas and the notation, and section 2 discusses some of the theoretical and practical implications of the model, including some concrete extensions, and some more speculative discussion.

International audience

International audience

The amplitude of localized quantum states in random or disordered media may exhibit long range exponential decay. We present here a theory that unveils the existence of an effective potential which finely governs the confinement of these states. In this picture, the boundaries of the localization subregions for low energy eigenfunctions correspond to the barriers of this effective potential, and the long range exponential decay characteristic of Anderson localization is explained as the consequence of multiple tunneling in the dense network of barriers created by this effective potential. Finally, we show that the Weyl's formula based on this potential turns out to be a remarkable approximation of the density of states for a large variety of 1D systems, periodic or random.