{ "paper_id": "H86-1015", "header": { "generated_with": "S2ORC 1.0.0", "date_generated": "2023-01-19T03:35:16.704971Z" }, "title": "", "authors": [], "year": "", "venue": null, "identifiers": {}, "abstract": "", "pdf_parse": { "paper_id": "H86-1015", "_pdf_hash": "", "abstract": [], "body_text": [ { "text": "Tree Adjolni-~ Grammars, or \"rAG's\", (Joshi, Levy & Takahashi 1975; Joshi 1983; Kroch & Joshi 1985) were developed as an alternative to the standard syntactic formalisms that are used in theoretical analyses of language.", "cite_spans": [ { "start": 37, "end": 67, "text": "(Joshi, Levy & Takahashi 1975;", "ref_id": null }, { "start": 68, "end": 79, "text": "Joshi 1983;", "ref_id": "BIBREF3" }, { "start": 80, "end": 99, "text": "Kroch & Joshi 1985)", "ref_id": "BIBREF4" } ], "ref_spans": [], "eq_spans": [], "section": "I, Albstraet", "sec_num": null }, { "text": "They are att~=,~ctive because they may provide just the aspects of context sensitive expressive power that actually appear in human languages while otherwise remaining context free.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "I, Albstraet", "sec_num": null }, { "text": "This paper describes how we have applied the thmry of Tree Adjoinln~ Grammars to natural language generation.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "I, Albstraet", "sec_num": null }, { "text": "We have been attracted to TAG's because their central operation-the extension of an \"initial\" phrase ~hucture tree through the inclusion, at very specifically constrained locations, of one or more \"auxiliary\" trees--corresponds directly to certain central operations of our own, performance-oriented theory.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "I, Albstraet", "sec_num": null }, { "text": "We begin by briefly describing TAG's as a formalism for phrase structure in a competence theory, and summarize the points in the theory of TAG's that are germaine to our own theory. We then consider generally the position of a grammar within the generation process, introducing our use of TAG'S through a contrast with how others have used systemic grammars. This takes us to the core results of our paper: using examples from our research with weft-written texts from newspapers, we walk through our TAG inspired treatments of raising and wh-movement, and show the correspondence of the TAG '%djunction\" operation and our \"attachment\" process.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "I, Albstraet", "sec_num": null }, { "text": "In the final section we discuss extensions to the theory, motivated by the way we use the operation corresponding to TAG'S\" adjunction in performance. This suggests that the competence theory of TAG's can be profitably projected to structures at the morphological level as well as the present syntactic level.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "I, Albstraet", "sec_num": null }, { "text": "The theoretical apparatus of a TAG consists of a pr/mitively defined set of \"elementary\" phrase structure trees, a '~xking\" relation that can be used to define dependency relations between two nodes within an elementary tree, and an \"adjunction\" operation that combines trees under specifiable constraints. The elementary trees are divided into two sets: init/a_l and auxiliary. Initial trees have only terminals at their leaves. Auxiliary trees are distinguished by having one non-terminal among their leaves; the category of this node must be the same as the category of the root. All elemental trees are \"minimal\" in the sense that they do not recurse on any non-terminal.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Tree Adjunction Grammars", "sec_num": "2." }, { "text": "A node N1 in an elementary tree may be linked (co-indexed) to a second node N2 in the same tree provided NI c-commands N2.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Tree Adjunction Grammars", "sec_num": "2." }, { "text": "Linking is used to indicate grammatically defined dependencies between nodes inch as mbcategorization relationships or filler-gap dependencies. Links are preserved (though \"stretched out\") when their tree is extended through adjunction; this is the mechanism TAG's use to represent unbounded dependencies.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Tree Adjunction Grammars", "sec_num": "2." }, { "text": "Sentence derivations start with an initial tree, and continue via the adjunction of an arbitrary number of auxiliary trees.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Tree Adjunction Grammars", "sec_num": "2." }, { "text": "To adjoin an auxiliary tree A with root category X to a initial (or derived) tree T, we first select mine node of category X within T to be the point at which the ad~.mction is to occur. Then (1) the subtree of T dominated by that instance of X (call it X') is removed from T, (2) the auxiliary tree A b knit into T at the position where X\" had been located, and (3) the subtree dominated by X\" b knit into A to replace the second occurence of the category X at T's frontier. The two trees have now been merged by '%pricing\" A into T, displacing the subtree of T at the point of the adjunction to the frontier of A.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Tree Adjunction Grammars", "sec_num": "2." }, { "text": "For example we could take the initial tree:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Tree Adjunction Grammars", "sec_num": "2." }, { "text": "IS\" Wh\u00b0i does IS John like e i ] ] (the subscript \"i\" indicates that the \"who\" and the trace \"e\" are linked) and adjoin to it the auxiliary tree:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Tree Adjunction Grammars", "sec_num": "2." }, { "text": "[S Bill befieves S ]", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Tree Adjunction Grammars", "sec_num": "2." }, { "text": "to produce the derived tree:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Tree Adjunction Grammars", "sec_num": "2." }, { "text": "IS\" Wh\u00b0i does IS Bill believe IS John likes e i ] ] ] Adjunction may be \"constrained\". The grammar writer may specify which specific trees may be adjoined to a given node in an elementary tree; if no specification is given the default is that there is no constraint and that any auxiliary tree may be adjoined to the node.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Tree Adjunction Grammars", "sec_num": "2." }, { "text": "A TAG specifies surface structure.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Key features of the theory of TAG's", "sec_num": "2.1" }, { "text": "There is no notion of derivation from deep structure in the theory of TAG's--the primitive trees are not transformed or otherwise changed once they are introduced into a text, only combined with other primitive trees. As Kroch and Joshi point out, this means that a TAG is incomplete as an account of the structure of a natural language, e.g. a TAG grammar will contain both an active and a passive form of the same verbal subcategorizafion pattern, without an theory-mediated description of the very close relationship between them.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Key features of the theory of TAG's", "sec_num": "2.1" }, { "text": "To our minds this is by no means a deficit. The procedural machinery that generative grammars have traditionally carried with them to characterize relations like that of active to passive has only gotten in the way of employing those characterizations in processing models of generation. This is because a generation model, like any theory of performance, has a procedural structure of its own and cannot coexist with an incompatible one, at least not while still operating efficiently or while retaining a simple mapping from its actual machine to the virtual machine that its authors put forward as their account of psycholinguistic data.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Key features of the theory of TAG's", "sec_num": "2.1" }, { "text": "Our own generator uses surface siJucture as its only expficitly represented linguistic level. Thus grammatical formalisms that dwell on the rules governing surface form are more useful to us than those that hide those rules in a deep to surface transformational process.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Key features of the theory of TAG's", "sec_num": "2.1" }, { "text": "A TAG Involvw the tmmlpuladon of very small dementary structmrw. This is because of the stip,,Indon that elementary trees may not induck recurtive nodes. It impliea that the sentences one tee, in everyday usage, e.g. newpaper texts, are the result of many tucemive adjunctions. This melds nicely with a move that we have mack in recent yeatt to view the conceptual representation from which generation proceeds as comiging of a heap of very small, reduadaatly related information units that have been deliberatebj selected by a text planning process from the total state of the kaowledge base at the time of utterance; each satch unit will correspoad in the final text to a head lexical item plus selected thematic arguments--a linguistic entity that is easily projected onto the elementary trees of a TAG.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Key features of the theory of TAG's", "sec_num": "2.1" }, { "text": "TAG theory ladmles only one operation, adJnnctlon, and otherwise makes no changes to the elementary trees that go into \u2022 text, This comports well with the indefibility stipulation in our model of generation, dnce selected text fragments can be used directly as specified by the grammar without the need for any later transformation.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Key features of the theory of TAG's", "sec_num": "2.1" }, { "text": "The composition options delimited by the constraints on adjunction given with a TAG define a space of alternative text forms which can correspond directly in generation to alternative conceptual relations among information units, alternatives in rhetorical intent, and alternatives in prose style.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Key features of the theory of TAG's", "sec_num": "2.1" }, { "text": "The mapping from TAG's as a formalism for competence theories of language to our formalism for generation is strikingly direct. Their adjuncti0n operation corresponds to our \"attachment process\"; their constraaints on adjunction correspond to our \"attachment points\"; their surface structure trees correspond to our surface structure trees. 1 We further hypothesize that two quite strong correspondence claims can be made, though considerably more experimentation and theorizing will have to be done with both formalisms before these claims can be confirmed.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Adapting TAG's to Generation", "sec_num": "3." }, { "text": "The primitive information units in realization specifications can be realized exclusively as one or another elementary tree as defined by a suitable TAG, i.e. linguistic criteria can be used in determining the proper modularity of the conceptual structure. 2", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "1.", "sec_num": null }, { "text": "Conversely, for any textual relationship which our generator would derive by the attachment of multiple information units into a tingle package, there is a corresponding rule of adjunction. Since we use attachment in the realization of nominal compouads like \"o// tanker\", this has the force of extending the domain of TAG analyses into morphology. (See section 7).", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "2.", "sec_num": null }, { "text": "1 Our model of generation does not employ the ample trees of labeled nodes that appear in most theoretical linguistic amtlytet Our turfa~ ttructurc incorporates the igmantic propertim of trees, but it also incJ,vt-,, rcifx=ttions of consdtmmt positions like \"subject\" or \"acntem:e\" and is bcttg~r characterized overall as an \"executable aequence of labeled positions\". We discuss this further in ::section 5.1. 21f this iqq:x)tlm is mcemfui, it has very comequenfial ;mnlicadonl for thz \"~.\u00a2\" of the information units that tbe text planner constructing tim realization specification can me, e.g. they would not be r~y.,~t at texts that include recmtiv, nodes. We will discuss this and other implications in \u2022 later ~.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "2.", "sec_num": null }, { "text": "To understand why we are looking at TAG's rather than some other formalism, one must first understand the role of grammar within our processing model. The following is a brief summary of the model; a more complete description can be found in McDonald & Pustejovsky [1985b] .", "cite_spans": [ { "start": 242, "end": 272, "text": "McDonald & Pustejovsky [1985b]", "ref_id": "BIBREF8" } ], "ref_spans": [], "eq_spans": [], "section": "l[ e Place of Gramnmr in a Theory of Generation", "sec_num": "4." }, { "text": "We have always had two complementary goals in our research: on the one hand our generation program has had to be of practica~l utility to the knowedge based expert systems that use it as part of a natural language interface.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "l[ e Place of Gramnmr in a Theory of Generation", "sec_num": "4." }, { "text": "This means that architecturally our generator has always been designed to produce text from conceptual specifications, ~plans\", developed by another program and consequently has had to be sensitive to the limitations and varying approaches of the present state of the art in conceptual representation.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "l[ e Place of Gramnmr in a Theory of Generation", "sec_num": "4." }, { "text": "At the same time, we want the architecture of the virtual machine that we abstract out of our program to be effective as a source of psycholinguistic hypotheses about the actual generation process that humans use; it should, for example, provide the basis for predictive accounts of human speech error behavior and apparent planning limitations. To achieve this, we have restricted ourselves to a highly constrained set of representations and operations, and have adopted strong and suggestive stipulations on our design such as high locality, information encapsulation, online quasi-realtime runtime performance, and indelibility) This restricts us as programmers, but disciplines us as theorists.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "l[ e Place of Gramnmr in a Theory of Generation", "sec_num": "4." }, { "text": "We see the process of generation as involving three temporally intermingled activities: 1determining what goals the utterance is to achieve, (2) planning what information content and rhetorical force will best meet those goals given the context, and (3) realiz/ng the specified information and rhetorical intent as a grammatical text.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "l[ e Place of Gramnmr in a Theory of Generation", "sec_num": "4." }, { "text": "Our linguistic component (henceforth LC), the Zetalisp program MUMBLE, handles the third of these activities, taking a \"realiTztion specification \"4 as input, and producing a stream of morphologically specialiTed words 5 as output.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "l[ e Place of Gramnmr in a Theory of Generation", "sec_num": "4." }, { "text": "As described in [McDonald 1984] , our LC is a \"description-directed\" process: it uses the structure of the realization specification it is given, plus the syntactic surface structure of the text in pro~ss (which it extends incrementally as the specification is realized) to directly control its actions, interpreting them as though they were sequential computer programs.", "cite_spans": [ { "start": 16, "end": 31, "text": "[McDonald 1984]", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "l[ e Place of Gramnmr in a Theory of Generation", "sec_num": "4." }, { "text": "This technique imposes strong demands on the descriptive formalima used for representing surface structure. For example, nodes and category labeis now designate actions the generator is to take (e.g. imposing scoping relations or constraining embedded decisions) and dictate the inclusion of function words and morphological specializations.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "l[ e Place of Gramnmr in a Theory of Generation", "sec_num": "4." }, { "text": "Of the egablished linguistic formalisms, systemic grammar [Halliday 1976 ] has always been the most important to AI researchers on generation. Two of the most important generation systems that have been developed, PROTEUS [Davey 1974] and NIGPJ-[Mann & Matthieuen 1983] , use systemic grammar, and others, including our own, have been strongly influenced by it. The reasons for this enthusiamn are central to the special concerns of generation.", "cite_spans": [ { "start": 58, "end": 72, "text": "[Halliday 1976", "ref_id": null }, { "start": 222, "end": 238, "text": "[Davey 1974] and", "ref_id": "BIBREF1" }, { "start": 239, "end": 252, "text": "NIGPJ-[Mann &", "ref_id": null }, { "start": 253, "end": 269, "text": "Matthieuen 1983]", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Gmm.n", "sec_num": null }, { "text": "Systemic grammars employ a functional vocabulary: they emphasize the uses to which language can be put--how languages achieve their speakers\" goals-rather than its formal structure.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Gmm.n", "sec_num": null }, { "text": "Since the generation process begins with goals, unlike the comprehem/on process which begins with structure, this orientation makes systemic grammars more immediately useful than, for example, transformational generative grammars or even procedurally oriented AI formalisms for language such as A TN's.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Gmm.n", "sec_num": null }, { "text": "The generation researcher's primary question is why use one construction rather than another--active instead of passive, \"the\" instead of \"a\". The principle device of a systemic grammar, the \"choice sy~em\", supports this question by highlighting how the constructions of the language are grouped into sets of alternatives. Choice systems provide an anchoring point for the rules of a theory of language use since it is natural to a~ociate the various semantic, discourse, or rhetorical criteria that bear on the selection of a given construction or feature with the choice system to which the construction belongs, thus providing the basis of a decision-procedure for selecting from its listed alternatives; the NIGEL system does precisely this in its \"chooser\" procedures.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Gmm.n", "sec_num": null }, { "text": "In our formalism we make use of the same information as a systemic grammar captures, however we have choosen to bundle it quite differently. The underlying reason for this is that our concern for psycholinguistic modeling and efficient processing takes precedence in our design decisions about how the facts of language and language use should be represented in a generator. It is thus instructive to look at the different kinds of linguistic information that a network of choice systems carry. In our system we distribute these to separate computational dev/ces.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Gmm.n", "sec_num": null }, { "text": "A generator must respect the constraints that dependencies impose and appreciate the impact they have on its realization options: for example that some subordinate clauses can not express tense or modality while main clauses are required to; or that a pronominal direct object forces particle movement while a lexical object leaves it optional. o Usage criteria. The decision procedures amoc/ated with each choice system are not a part of the grammar per se, although they are naturally associated with it and organized by it. Also most systemic grammars include very abstract featur~ such as \"generic reference\" or \"completed action\", which cross-correlate the language's surface features, and thus are more controllers of why a construct is used rather than conshucts themselves. o Coordinated structural alternatives. A sentence may be either active or passive, either a question or a statement. By groupin 8 these alternatives into systems and using these systems exdusively when constructing a text, one is guaranteed not to combine inconsistent structural features.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "o Dependencies among structural features:", "sec_num": null }, { "text": "\"7", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "o Dependencies among structural features:", "sec_num": null }, { "text": "o Efficient ordering of choices. The network that connect, choice t~stems provides a natural path between decisiom, which if followed strictly guarentees that a choice will not be made unlm it is required, and that it will not be made before any of the choic_~___ that it it itself dependent upon, insuring that it can 151 be made indelibly. ~ o Typology of sm'face structure. Almost by accident (dnce its specification is dhgtributed throughout all of the systems impficitly), the grammar determines the pattern of dominance and comtituency relationshiln of the text. While not a principle of the theozy, the trees of clanses, NP% etc. in systemic grammars tend to be shallow and broad.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "o Dependencies among structural features:", "sec_num": null }, { "text": "We believe, but have not yet established, that equivalence transformations can be defined that would take a systemic grammar as a q3ecification to construct the alternative devices that we use in our generator (or auement devices that derive from other sources, e.g. a TAG) by decomposing the information in the systemic grammar along the lines just listed and redistributing it.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "o Dependencies among structural features:", "sec_num": null }, { "text": "One of the task domains we are currently developing involves newspaper reports of current events. We are \"reverse engineering\" leading paragraphs from actual newspaper articles to produce narrow but complex conceptual representation, and then desiEning realization specifications--plans--that will lead our LC to reconstruct the original text or motivated variations on it. We have adopted this domain because the news reporting task, with its requirement of communicating what is new and si!,nificant in an event as well as the event itself, appears to impose exceptionally rich constraints on the selection of what conceptual information to report and on what syntactic constructions to use in reporting it (see discussion in Ciipplnger & McDonald [1983 D . We expect to fred out how much complexity a realization specification requires in order to motivate such carefully composed texts; this will later guide us in designing a text planner with sufficient capabilities to construct such specifications on its own.", "cite_spans": [ { "start": 728, "end": 757, "text": "Ciipplnger & McDonald [1983 D", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Example Analyses", "sec_num": "5." }, { "text": "Our examples are drawn from the text fragment below (Associated Press, 12/23/84); the realization specification we use to reproduce the text follows. This realization speOJicatiou represents the structured object which gives the toplevel plan for this utterance. Symbols preoeded by colons indicate particular features of the utterance.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Example Analyses", "sec_num": "5." }, { "text": "The two expressions in parentheses are the content items of the specification and are restricted to appear in the utterance in that order.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "The first symbol in each expr~on is a label indicating the function of that item within the plan; embedded items appearing in angle brackets are information units from the current-events knowledge base.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "Obviously this plan must be considerably refined before it could serve as a proximal source for the text; that is why we point out that it is a \"toplever' plan. It is a specification for the general otltline of the utterance which must be fleshed out by recursive planning once its reafization has begun and the LC can supply a linguistic context to further constrain the choices for the units and the rhetorical features.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "For present purposes, the key fact to appreciate about this realization specification is how different it is in form from the surface structure.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "One cannot produce the cited text simply by traversing and \"reading out\" the elements of the specification as though one were doing direct production. Structural rearrangements are required, and these must be done under the oontrol of constraints which can only be stated in linguistic vocabulary with terms like \"subject\" or \"raising\".", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "The first unit in the spcc/fication, ~, is a relation over two other units. It indicates that a commonality between the two has been noticed and deemed significant in the underlying representation of the event.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "The present LC always realizes such relations by mergil~ the realizations of the two units. If nothing else occurred, this would give us the text \"Two oil tankers were hit by missiles\".", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "As it happens, however, a pending rhetorical constraint from the realization specification, ~svents-r~ulre-\u00a2erUfk~on-u4o-source will force the addition of yet another information unit, 6 the reporting event by the news serv/ce that announced the aledged event (e.g. a press release from Iraq, Reuters, etc.). In this case the \"coatent\" of the reporting event is the two damage-repor~ which have already been planned for inclusion in the utterance as part of the '~trticulars\" part of the specification. Let us look closely at how that reportiing event unit is folded into surface structure.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "When not itself the focus of attention, a reporting event is typically realized as '~u3-and-so said X\", that is, the content of the report is more important than the report itself; whatever significance the report or its source has as news will be indicated subtly through \"which of the alternative realizations below is selected for it. 7 6 We will not discuss the mechanism by which features in the specification inlluetg~ realization. Realization qgcifi~fions of the complexity of this emsmpiz are still very new in our research and we arc unsure whether the process is better organized at the mnceptual level directing \u2022 composition process within the planning componeat (during one of the recursive invocations) or within the LC In our LC, these alternative \"choices\" are grouped together into a \"realiTation class\" as shown in F'tgure 3. Our realiTafion classes have their historic orisin5 in the choice t3nltem$ of systemic grammar, though they are very different in almost every concrete detail.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "The most important difference of interest theoretically is that while wstemic choice systems select among single alternative features (e.g. p~ve, gerundive), realization classes select among entire surface structure fxa~,ments at a time (which might be seen as prespecified realizations of bundles of features).", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "That is, our approach to generation calls for us to organize our decision procedures so as to select the values for a number of linguhtic features simultaneously in one choice where a systemic grammar would make the selection incrementally. 8 8 The standard technique of using choicc systems to control ~ activc ~.Icction of utterance features b employed by ~ most well-known applications of systa:nic grammars to ge.J,~ation (i.e. the work of Davey [1974] and Mann and Matthiessen [1983D. Howover very reo~t work with systemic grammars at Edinburgh by Patten [1985] depa~ from this technique.", "cite_spans": [ { "start": 444, "end": 456, "text": "Davey [1974]", "ref_id": "BIBREF1" }, { "start": 553, "end": 566, "text": "Patten [1985]", "ref_id": "BIBREF9" } ], "ref_spans": [], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "Patten uses a semantic-level plannin~ coml~lte~t to directly ~ grOUpl of features at the rightward, \"output\", rode of a systemic network, and then works hackwarde through the network to determine what other, not semaficcaUy features must be added to the text for it to be grammatical; control is thus outside the grammar proper, with gramnunr rule, rckqptted to constraint specification only. We are intrigued by this technique and look forward to its further dcvelopmcnt. ; e.g. =L/oyds reports lraq hit two tankers.\" ; encompasses variations with and without that, and ; also tenseless complements like =John believes him Returning to our example, we are now faced now with the need to incorporate a unit denoting the report of the Iraqi attacks into the utterance to act as a certification of the #<~-by-rmsaes> events.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "This will be done using the realization class be/ieve-vedm; the class is applicable to any information unit of the form report(source, info) (and others). It determines the realization of such units l?oth when they appear in issolation and, as in the present case, when they are to augment an utterance corresponding to one of their arguments.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "From this realization class the choice raise-VERB-In, PROP will be selected since (1) the fact that two ships were hit is most ~gnificant, meaning that the focus will be on the information and not the source (n.b. when the class executes the source t'aq will be bound to the a0ent parameter and the information about the missile hits to the proposaM, n parameter); (2) there is no rhetorical motivation for us to occupy space in the tint sentence with the sources of the report since they have already been planned to follow.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "These conditions are sensed by attached pxocedures associated with the characteristics that annotate the choice (i.e. focta and menti0md-elsewhem).", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "Since the PROP is ah'cady in place in the mrface structure tree, the LC will be interpreting ralse-VERB.Inlo-PROP as a q)eciflcation of how it may fold the auxiliary tree for reported into the tree for Two oil tankers were hit by missiles Friday in the Gulf. This corresponds to the TAG analym in F'tgure 4 [Kroch & Joshi 1985] . In/tiaI and amdUlary trees for RalMng4e.eubject", "cite_spans": [ { "start": 307, "end": 327, "text": "[Kroch & Joshi 1985]", "ref_id": "BIBREF4" } ], "ref_spans": [], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "The initial tree for Two oil tankers were hit by missiles, I1, may be extended at its INFL\" node as indicated by the constraint given in parenthesis by that node. Figure 5 shows the tree after the auxiliary tree A 2, named by that constraint, has been adjoincd.", "cite_spans": [], "ref_spans": [ { "start": 163, "end": 171, "text": "Figure 5", "ref_id": null } ], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "Notice that the original INFL\" of Figure 4 is now in the complement position of report, giving us the sentence Two oil tankers were reported hit by missiles. ", "cite_spans": [], "ref_spans": [ { "start": 34, "end": 42, "text": "Figure 4", "ref_id": null } ], "eq_spans": [], "section": "\"LONDON -", "sec_num": null }, { "text": "As readers of any of our earlier papers arc aware, we do not employ a conventional tree notation in our LC. A generation model places its own kinds of demands on the representation of surface structure, and these lead to principled departures from the conventions adopted by theoretical linguists. Figure 6 shows the surface structure as our LC would actuary represent it just before the moment when the adjunction is made. Figure 6 Surfam structure in pathnotation", "cite_spans": [], "ref_spans": [ { "start": 298, "end": 306, "text": "Figure 6", "ref_id": null }, { "start": 424, "end": 432, "text": "Figure 6", "ref_id": null } ], "eq_spans": [], "section": "5.I Path Notation", "sec_num": null }, { "text": "We call this representation path notat/on because it defines the path that our LC follows. Formally the structure is not a tree but a unidirectional linked list whose formation rules obey the axioms of a tree (e.g. any path \"down\" through a given node must eventually pass back \"up\" through that same node).", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "5.I Path Notation", "sec_num": null }, { "text": "The path consists of a stream of entities representing phrasal nodes, constituent positions (indicated by square brackets), instances of information units (in boldface), instances of words, and activated attachment points (the labeled circle under the predicate; see next section).", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "5.I Path Notation", "sec_num": null }, { "text": "The various symbols in the figure (e.g. sentence, predicate, etc.) have attached procedures that are activated as the point of speech moves along the path, a process we call '~phrase ~iJucture execution\".", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "5.I Path Notation", "sec_num": null }, { "text": "Phrase ttlucture execution is the mean.~ by which grammatical constraints are imposed on embedded decisions and function words and grammatical morphemes are produced. (For discussion see McDonald [1984] .)", "cite_spans": [ { "start": 187, "end": 202, "text": "McDonald [1984]", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "5.I Path Notation", "sec_num": null }, { "text": "Once one has begun to think of surface structure as a travenal path, it is a short step to ima~inln~ being able to cut the path and '~plice in\" additional position sequence. 9 This ~licing operation inherits a natural set of constraints on the ldnds of distortions that it can perform, since, by the indelibility stipulation, existing position sequences can not be destroyed or rethreaded. It is our impression that these constraints will turn out to be formally the same as those ~ of a TAG, but we have not yet carried out the detailed analyses to confirm this.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "5.I Path Notation", "sec_num": null }, { "text": "9The fem-ueity of cutting the mzrface structure and insetting new eequences that change the \u2022 linguistic context of pmitiom akeady in place has been in our thmry of generation since 1978, when we used it to implement rat~Ing veto whooe rhetorical fogee was the mine as \"hedging\" advedbs like poax//dy. Our pre~at, much more e~mtve use of thia device as the core of a distim:t attachment procem dates from the summer of 1984.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "5.I Path Notation", "sec_num": null }, { "text": "The TAG formalism allows a grammar writer to define \"constraints\" by annotating the nodes of elementary trees with lists indicating what auxiliary trees may be adjoined to them (including \"any\" or \"none\"). l\u00b0 In a similar manner the \"choices\" in our realization cl~which by our hypothesis can be taken to always correspond to TAG elementary trees--include specifications of the attachment po/nts at which new information units can be incorporated into the surface structure path they defme. Rather than being constraints on an otherwise freely applying operation, as in a TAG, attachment points are actual ob~cts interposed in the path notation of the surface structure. A list of the attachment points active at any moment is maintained by the attachment process and consulted whenever an information unit needs to be added. Most units could be attached at any of several points, with the decision being made on the basis of what would be most consistent with the desired prose style (cf. McDonald and Pustejovsky [1985aD. When one of the points is selected it is instantiated, usually splicing in new surface structure in the process, and the new unit added at a designated position within the new structure. Figure 7 shows our present definition of the attachment point that ultimately leads to the addition of \"was reported\". ; where the existing contents go e~ezt~-oew-peod~a~-polnts cholcm-tl~-Introduc~lt", "cite_spans": [ { "start": 985, "end": 1023, "text": "(cf. McDonald and Pustejovsky [1985aD.", "ref_id": null } ], "ref_spans": [ { "start": 1211, "end": 1219, "text": "Figure 7", "ref_id": null } ], "eq_spans": [], "section": "$.2 Attaehm_m,t Peints", "sec_num": null }, { "text": "x~oeee-~te~ ~et~t \"prececate))", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "$.2 Attaehm_m,t Peints", "sec_num": null }, { "text": "This attachment point goes with any choice (elementary tree) that includes a constituent position labeled ia~dUkate.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Figure 7 The attltchmeat-lpoint wed by was reported", "sec_num": null }, { "text": "It is placed in the position path immediately after (or \"under\") that position (see Figure 6) , where it is available to any new unit that passes the indicated requirements.", "cite_spans": [], "ref_spans": [ { "start": 84, "end": 93, "text": "Figure 6)", "ref_id": null } ], "eq_spans": [], "section": "Figure 7 The attltchmeat-lpoint wed by was reported", "sec_num": null }, { "text": "When this a.~chment is selected, it builds a new VP node that has the old VP as one of its comtituents, then spUces this new node into the path in its place as shown in F~u,~ 7.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Figure 7 The attltchmeat-lpoint wed by was reported", "sec_num": null }, { "text": "The unit being attached, e.g. the report of the attack on the two oil tankers, is made the verb of the new VP. Later, once the phrase structure execution process has walked into the new VP and reached that verb position, the unit's realization class (belief-verbs) will be consulted and a choice selected that is consistent with the grammatical constraints of being a verb (i.e. a conventional variant on the raise-VERB4nto-PROP choice), 8ivi~ us \"wos reported\". is a consequence of the fact that we are working with a performance model of generation that must show explicitly how conceptual information units are rendered into texts as part of a psycholinguisticaUy plausible process, while a TAG b a formalism for competence theories that only hoe4 to specify the syntactic itmcture of the grammatical strings of a language. This is a significant difference, but not one that should stand in our way in comparing what the two theories have to offer each other. Comequently in the rest of this paper we will omit the d~aill of the path notation and attachment point def'mitions to facilitate the comparison of theoretical issues.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Figure 7 The attltchmeat-lpoint wed by was reported", "sec_num": null }, { "text": "Earlier we illustrated the TAG concept of \"linking\" by showing how one would start with an initial tree consisting of the /nnermost clause of a question plus the fronted wh-phrase and then build outward by successively adjoining the desired auxiliary phrases to the S node that intervenes between the wh-phrase and the clause. Wh-questions are thus built from the bottom up, as in fact is any sentence involving verbs taking sentential complements.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Generating qua/ions m/ng a TAG version of wh-movement", "sec_num": "6." }, { "text": "analylis has the desirable property of allowing one to state the dependendes between the Wh-phrase and the gap as a local relation on a single elementary tree, eliminating the need to Include any machinery for movement in the theory.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Generating qua/ions m/ng a TAG version of wh-movement", "sec_num": "6." }, { "text": "All unbounded dependendes now derive from adjunctions (which, as far as the grammar is concerned, can be made without limit), rather than to the expficit migration of a constituent acrms clauses.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Generating qua/ions m/ng a TAG version of wh-movement", "sec_num": "6." }, { "text": "We also find this locality property to be desirable, and use an analogous procedure in our production of questiona and other kinds of Whquestions and unbounded dependency constructions.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Generating qua/ions m/ng a TAG version of wh-movement", "sec_num": "6." }, { "text": "This \"bottom-up\" design has consequences for how the realization specifications for these constructions must be organized. In particular, the logician's usual representation of sentential complement verbs as higher operators is not tenable in that role. For example we cannot have the source of, say, How many ships did Reuters report that Iraq had said it attacked? be the expreuion: Lambda(quantlty-of-shlps) . report(Reuters, sty(Lraq, attack(Iraq, quantity-of-ships))) Such an expression defines a natural sequence of exposure when used as realization specification, namely that one realize the Lmnlght operator first, the report operator second, the sty third, and so on. A local TAG analysis of Wh-movement requires us to have the Lambda and the expression containing its matrix trace, attach, be present in a single \"layer\" of the specification, otherwise we would be forced to violate one of the strong principles of our theory of generation, namely that the characteristics in a realization class may \"see\" only the immediate arguments of the unit being realized; they may not' look \"inside\" those arguments to subsequent levels of conceptual structure.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Generating qua/ions m/ng a TAG version of wh-movement", "sec_num": "6." }, { "text": "This principle has served t~s well, and we are disinclined to give it up without a very compelling reason. We elected instead to give up the internal representation of sentential complement verb texts as tingle expressions. This move was easy for us to make since such expreuions are awkward to manipulate in the \"East Coast\" style frame knowledge bases that we use in our own reasonin S programs, and we have preferred a representational style with redundant, smaller sized conceptual units for quite some time.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Generating qua/ions m/ng a TAG version of wh-movement", "sec_num": "6." }, { "text": "The representation~ we use instead amounts to breaking up the logical expression into individual units and allowing them to include references to each other. U I = lambda(quantity-of-shipa) . attack(Iraq,quantity-of-ships) U 2 = sty(Iraq, U1) u 3 : repo.(Reuten, U2)", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Generating qua/ions m/ng a TAG version of wh-movement", "sec_num": "6." }, { "text": "Given such a network as the realization specification, the LC must have some principle by which to judge where to start: which unit should form the basis of the surface mucture to which the others are then attached? A natural principle to adopt is to begin with the '\u00b0rash\" unit, i~. the one that does not mention any other units in its definition.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Generating qua/ions m/ng a TAG version of wh-movement", "sec_num": "6." }, { "text": "We are comiderin s adopting the policy that such units should be allowed only realizations as initial trees while units whose definition involves \"pointing to\" (naming) other units shouldbe allowed only rea!iza\" tions as auxiliary trees. We have not, however, worked through all of the ramifications such a policy might have on other parts of our generation model; without yet knowing whether it would improve or degrade the other parts of our theory, we are reluctant to assert it as one of our hypotheses relating our generation model to TAG's.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Generating qua/ions m/ng a TAG version of wh-movement", "sec_num": "6." }, { "text": "Given that three part source, the realization of the question is fairly straightforward (See Figure 9) . The Lambda expression is assigned a realization class for clausal Wh constructions, whereupon the \u00a9xUscted argument quantlty.of.shlps is placed in COMP, and the body of the expression is placed in the HEAD position. At the same time, the two instances of qumd/ty-of-ehIp8 are specially marked. The one in COMP is ass/gned to the realization class for Wh phrases appropriate to quantity (e.g. it will have the choice how many X and possibly related choices such as of which and other variants appropriate to relative clauses or other positions where Wh constructions can be used). Simultaneously the instance of quanflty-ef-eidps in the argument position of the head frame attack is assigned to the realization class for Wh-trace. These two specializations are the equivalent, in our model, of the TAG linking relation. The two pending units, U 2 and U3, are then attached to this matrix, submerging first the attach unit and then U 2 into complement positions.", "cite_spans": [], "ref_spans": [ { "start": 93, "end": 102, "text": "Figure 9)", "ref_id": null } ], "eq_spans": [], "section": "Generating qua/ions m/ng a TAG version of wh-movement", "sec_num": "6." }, { "text": "7. Extensions to'the 'l]~eory of TAG Context-free grammars are able to express the word formation processes that seem to exist for natural language, (cf. Williams [1981] , Selkirk [1982] ). A TAG analysis of inch a grammar seems like a natural application to the current version of the theory (d. Puste~k-y (in preparation)). To illustrate our point, consider compounding rules in English. We can say that for a context-free grammar for word formation, Gw, there is a TAG, T w, that is equivalent to G w (d. Figur~ 10 and 11) . Now conmder the compound , =oil tanker terminal, taken from the newspaper reporting domain, and its derivation in TAG theory, shown in Figure 12 .", "cite_spans": [ { "start": 154, "end": 169, "text": "Williams [1981]", "ref_id": "BIBREF11" }, { "start": 180, "end": 186, "text": "[1982]", "ref_id": null } ], "ref_spans": [ { "start": 508, "end": 525, "text": "Figur~ 10 and 11)", "ref_id": null }, { "start": 663, "end": 672, "text": "Figure 12", "ref_id": "FIGREF0" } ], "eq_spans": [], "section": "Generating qua/ions m/ng a TAG version of wh-movement", "sec_num": "6." }, { "text": "11 Whether the word formation component should in fact have the power of a TAG or CFG is an open question. Langendoen [1981] discusses the possibility that a f'mite state grammar might be sufficient for the generative capacity of natural language word formation components. Let us compare this derivation to the process used by the LC. The underlying information units from which this compound is derived in our system are shown below. The planner has decided that the units below need to be communicated in order to adequately express the concept. The top-level unit in this bundle is #. The first unit to be positioned in the mrface structure is U 1, and appears as the head of an NP. There is an attachment point on this position, however, which allows for the possibility of expressing U 2 prenominally. One of the choices associated with this unit is a compound structuro--expre~ed in terms of an auxiliary tree. A snapshot at this point in the derivation shows the following structure.", "cite_spans": [ { "start": 107, "end": 124, "text": "Langendoen [1981]", "ref_id": "BIBREF5" } ], "ref_spans": [], "eq_spans": [], "section": "Generating qua/ions m/ng a TAG version of wh-movement", "sec_num": "6." }, { "text": "[C~,.~ U2 ] Ol ]", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Generating qua/ions m/ng a TAG version of wh-movement", "sec_num": "6." }, { "text": "The next unit opened up in this structure is U 3, which also allows for attachment prenominally. Thus an auxiliary tree corresponding to U 4 is introduced, giving us the structure below: ~ ~.~ u4 ] u~ u 11", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Generating qua/ions m/ng a TAG version of wh-movement", "sec_num": "6." }, { "text": "The selectional constraints imposed by the structural positioning of information unit U 4 allows only a compounding choice. Had there been no word-level compound realization option, we would have worked our way into a corner without expressing the relation between # and #. Because of this it may be better to view units such as U 4 as being associated directly with a lexical compounded form, i.e. oil tanker. This partial solution, however, would not speak to the problem of active word formation in the language. Furthermore, it would be interesting to compare the strategic decisions made by a generation system with those planning mistakes made by humans when speaking. This is an aspect of generation that merits much further research.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Generating qua/ions m/ng a TAG version of wh-movement", "sec_num": "6." }, { "text": "\"~ty\" in a computation requires that no action of a process (making decisions, constructing represeatations, chan8~ state, etc.) can be tramparently undone once it has been performed. Many nonbacktracking, nonfntra~ program designs have this property; it is our term for whatMarcus [1980] referred to as the property of being \"strictly determlnhtic'.4A realization specification can informally be taken to correspond to what many researchers, partioti~iy p~hok~t.% lhink of Its the \"me~tge love.J\" g~Uttion of a text.5 Which is to say tb~t it presently produces written rath~ .h\u2022n ~ok~ U~UI. We e~rp\u00a2~ tO work with speech output shortly, howev~, sad the need to support the ~tational basis of an intonational contour is begi~n\u00a3 to influence our dcsigns for constituency patterns in surface structure.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "", "sec_num": null }, { "text": "Constraints of this sort are an inovation introduced in Kroch & Joshi[1985].Previous versions of TAG theory allowed \"context sensitive\" constraint specifications that in fact were never exploited. The present constraints are more attractive formally since they must be stated locally to a single tree.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "", "sec_num": null } ], "back_matter": [ { "text": "This research has been mpterminaled in part by contract N0014-85-K4)017 from the Defense Advanced Research Projects Agency. We would like to thank Marie Vaughan for help in the preparation of this text.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Acknowledgements", "sec_num": "8." } ], "bib_entries": { "BIBREF0": { "ref_id": "b0", "title": "Why Good Writing is Easier to Understand", "authors": [ { "first": "&", "middle": [], "last": "Clippinger", "suffix": "" }, { "first": "", "middle": [], "last": "Mcdonald", "suffix": "" } ], "year": 1983, "venue": "Proc. IJCAI-83", "volume": "", "issue": "", "pages": "730--732", "other_ids": {}, "num": null, "urls": [], "raw_text": "Clippinger, & McDonald (1983) \"Why Good Writing is Easier to Understand\", Proc. IJCAI-83, pp. 730-732.", "links": null }, "BIBREF1": { "ref_id": "b1", "title": "Dbcourse Production, Ph.D. Dissertation, Edinburgh University", "authors": [ { "first": "", "middle": [], "last": "Davey", "suffix": "" } ], "year": 1974, "venue": "", "volume": "", "issue": "", "pages": "", "other_ids": {}, "num": null, "urls": [], "raw_text": "Davey (1974) Dbcourse Production, Ph.D. Dissertation, Edinburgh University; publi~ed in 1979 by Edinburgh University Press.", "links": null }, "BIBREF2": { "ref_id": "b2", "title": "Halliday (1976) System and Function in Language", "authors": [], "year": null, "venue": "", "volume": "", "issue": "", "pages": "", "other_ids": {}, "num": null, "urls": [], "raw_text": "Halliday (1976) System and Function in Language, Oxford University Press.", "links": null }, "BIBREF3": { "ref_id": "b3", "title": "How Much Context-Sensitivity is Required to Provide Reasonable Structural Descriptions: Tree Adjoining Grammars", "authors": [ { "first": "", "middle": [], "last": "Joshi", "suffix": "" } ], "year": 1983, "venue": "Karttunen, & Zwicky (ecls.) Natural Language Processing: Psycholin=~2ulstlc , Comimtatlonal, and Theoretical Perspectives", "volume": "", "issue": "", "pages": "", "other_ids": {}, "num": null, "urls": [], "raw_text": "Joshi (1983) \"How Much Context-Sensitivity is Required to Provide Reasonable Structural Descriptions: Tree Adjoining Grammars\", preprint to appear in Dowty, Karttunen, & Zwicky (ecls.) Natural Language Processing: Psycholin=~2ulstlc , Comimtatlonal, and Theoretical Perspectives, Cambridge University Press.", "links": null }, "BIBREF4": { "ref_id": "b4", "title": "The Linguistic Relevance of Tree Adjoining Grammar", "authors": [ { "first": "T", "middle": [], "last": "Kroch", "suffix": "" }, { "first": "A", "middle": [], "last": "Joshi", "suffix": "" } ], "year": 1985, "venue": "", "volume": "", "issue": "", "pages": "", "other_ids": {}, "num": null, "urls": [], "raw_text": "Kroch, T. and A. Joshi (1985) \"The Linguistic Relevance of Tree Adjoining Grammar\", University of Penosylvania, Dept. of Computer and Information Science.", "links": null }, "BIBREF5": { "ref_id": "b5", "title": "q'he Generative Capacity of Word-Formation Components", "authors": [ { "first": "D", "middle": [ "T" ], "last": "Langendoen", "suffix": "" } ], "year": 1981, "venue": "Linguistic Inquiry", "volume": "12", "issue": "2", "pages": "", "other_ids": {}, "num": null, "urls": [], "raw_text": "Langendoen, D.T. (1981) 'q'he Generative Capacity of Word-Formation Components\", Linguistic Inquiry, Volume 12.2", "links": null }, "BIBREF6": { "ref_id": "b6", "title": "Ni&el: A Systemic Grammar for Text Generation", "authors": [ { "first": "", "middle": [], "last": "Mann & Matthiessen", "suffix": "" } ], "year": 1983, "venue": "Systemic Perspectives on Discourse", "volume": "", "issue": "", "pages": "", "other_ids": {}, "num": null, "urls": [], "raw_text": "Mann & Matthiessen (1983)Ni&el: A Systemic Grammar for Text Generation, in Freedle (ed.) Systemic Perspectives on Discourse, Ablex.", "links": null }, "BIBREF7": { "ref_id": "b7", "title": "Description Directed Control: Its Implications for Natu~ral Language Generation", "authors": [ { "first": "", "middle": [], "last": "Marcus", "suffix": "" } ], "year": 1980, "venue": "", "volume": "", "issue": "", "pages": "", "other_ids": {}, "num": null, "urls": [], "raw_text": "Marcus (1980) A Theory of Syntactic Recognition for Natural Language, MIT Press. McDonald (1984) \"Description Directed Control: Its Implications for Natu~ral Language Generation\", in Cercone (ed.) Cemlmtatlonal IAngulstlcs, Pergamon Press.", "links": null }, "BIBREF8": { "ref_id": "b8", "title": "SAMSON: a computational theory of prose style in generation", "authors": [ { "first": "&", "middle": [], "last": "Mcdonald", "suffix": "" }, { "first": "", "middle": [], "last": "Pustejovsky", "suffix": "" } ], "year": 1985, "venue": "Proceedings of the 1985 meeting of the European Association for Computational Linguistics", "volume": "", "issue": "", "pages": "", "other_ids": {}, "num": null, "urls": [], "raw_text": "McDonald & Pustejovsky (1985a) \"SAMSON: a computational theory of prose style in generation\", Proceedings of the 1985 meeting of the European Association for Computational Linguistics. (1985b) \"Description-Directed Natural Language Generation\", Proceedings of IJCAI-85, WXaufmann Inc., Los Altos CA.", "links": null }, "BIBREF9": { "ref_id": "b9", "title": "A Problem Solving Approach to Generating Text from Systemic Grammars", "authors": [ { "first": "T", "middle": [], "last": "Patten", "suffix": "" } ], "year": 1985, "venue": "Proceedings of the 1985 meeting of the European Association for Computational Linguistics", "volume": "", "issue": "", "pages": "", "other_ids": {}, "num": null, "urls": [], "raw_text": "Patten T. (1985) \"A Problem Solving Approach to Generating Text from Systemic Grammars\", Proceedings of the 1985 meeting of the European Association for Computational Linguistics.", "links": null }, "BIBREF10": { "ref_id": "b10", "title": "Word Formation in Tree Adjoining Grammars\" Selkirk (1982) The Syntax of Words", "authors": [ { "first": "J", "middle": [], "last": "Pustejovtky", "suffix": "" } ], "year": null, "venue": "", "volume": "", "issue": "", "pages": "", "other_ids": {}, "num": null, "urls": [], "raw_text": "Pustejovtky, J. (In Preparation) \"Word Formation in Tree Adjoining Grammars\" Selkirk (1982) The Syntax of Words, MIT Press.", "links": null }, "BIBREF11": { "ref_id": "b11", "title": "Argument Structure and Morphology", "authors": [ { "first": "", "middle": [], "last": "Williams", "suffix": "" } ], "year": 1981, "venue": "The Linguistic Review", "volume": "1", "issue": "", "pages": "81--114", "other_ids": {}, "num": null, "urls": [], "raw_text": "Williams (1981) \"Argument Structure and Morphology\" The Linguistic Review, 1, 81-114.", "links": null } }, "ref_entries": { "FIGREF0": { "num": null, "uris": null, "type_str": "figure", "text": "Possibilities for expressing report(source, info) in newpaper prose" }, "FIGREF2": { "num": null, "uris": null, "type_str": "figure", "text": "to be a fool.\" ( (raise-VERB-Into-PROP (passlvlze verb| prop) dame focus((aOe.t prop)) menUoned4sewtmm(aoent)) ; \"Two tankers were reported to have been hit\" ( (It-VERB-PROP ve, b prop) dame ~erat~e(agent) ) ; e.g. =it is reported that 2 tankers were hit.\" ( Oeft,.dlslocated~ agent ved) prop) ciauu de-empemize(se~ ; \"Two tankers were hit, Gulf sources saM.\")) Realization class assigned to report(l~J~t(_)" }, "FIGREF3": { "num": null, "uris": null, "type_str": "figure", "text": "Figure $ After embedding report" }, "FIGREF4": { "num": null, "uris": null, "type_str": "figure", "text": "(define-attachment-point attach-raJs~ng.~'edcate reference-poinm ( (~\"~l~.~elot \u00b0pr~.ate phrase) zttach-under ) (vp-lrdinltlve-cong31emeot) ; specification of new phrase verb ; where the unit being attached goes ~inttJve-cor~)" }, "FIGREF5": { "num": null, "uris": null, "type_str": "figure", "text": "by-mi--ile----> Figure 8 'nze path after\" attachment From this discussion one can see that our treatment of attachment uses two gructures, an attachment point and a choice, where a TAG would only use one structure, an auxiliary tree. ~" }, "FIGREF7": { "num": null, "uris": null, "type_str": "figure", "text": "Figure 11 TAG Fragment for Word Formation" }, "FIGREF8": { "num": null, "uris": null, "type_str": "figure", "text": "Derivation of oil tanker terminal" }, "TABREF0": { "num": null, "type_str": "table", "content": "
Two oil tankers, the Norwegian-ownedThorshavet end a
(the-day\" Hvents-~-the-GU~-tanker-war
~1as-ttHiource
(mn~-ever4 #~me-ever~-~lpe_vnryk,o-om{em
#<hlbby-rnbalm Thomhavel>
#<~t-by-mbsaes Ubedan> >
~nmual ~<nurrter-of-sP~ps-I~a 2> Jde y-the-ps )
(partkxlars #<damage-r~xxt Thorahavet O~o-omc~s>
#<da.~e-repo,t Uber~n Uoyds> ))
", "text": "Uben'en-registered v~__el, were reported to have been hit by missiles Friday in the Guff.", "html": null }, "TABREF1": { "num": null, "type_str": "table", "content": "
.. mediating a selection between anticipated alternatives. \u2022 inconclusivc. Rmdt text de.empha~ report Two tankers were hit, Gulf shippin& sources said. At this point our design experiments are source b 0yea ebewhere Two tankers were reported hit. 7 nedred cbmu er ae emiMmMxe report Iraq reported it hit two tankers.
", "text": "These sentenees are s.rfificial; meal ones would be considerably longer. Interestingly, o:rtain other syntactically permissable ~,~,~oes such ss \"/t WaS ~oorted that\" do not occur in say of the texts we have examined. Perhaps the \"lead ~ position is too tmporUmt to waste on a proneun.", "html": null } } } }