From: AAAI-84 Proceedings. Copyright ©1984, AAAI (www.aaai.org). All rights reserved. Referential Determinism and Computational Efficiency: Posting Constraintsfrom DeepStructure* Gavan Duffy and John C. Mallet-y Department Massachusetts of Political Institute Cambridge Arpanet: transformational structures. Instead deep structures conjunction they wrth adopt a reference ccnstitutes create a surface-tnterpretlve into architecture to include We Determinism semantic constraint on of that our combination theories referential of deep structures non-determinism immediate in constramt-posting, We find at SRI on network. In syntactic We parsers to NP resolution. We show the and the that by their tl uses in may the hypothesis structure, rejected, IS and start reasoner, i!s maximized when components is it again. does backtrack, erase resources not It is and then, if non-deterministic. It can hypothesize some become Its improves. input perform can As more performance its necessarily require or all available available revision of its to such resources and when a are all other deterministically. and view is consistent sympathetic speclficatlons. to Sentence of Interpretation example. hypothesis for crucial Relerent/al this a se!7tence desires analysis, necessary IS another Prefer linguists’ Marcus’ for of course, sentence aspect. that Hypothesis parsimonious does We offer [23] grammar not exhaust understanding. Defermimsm analysis Determinism argue constraint-posting together that below reference they minimize satisfy referential tl this the provides terms view, puts signat (;~ublic) [27] reference. correspondence recoverrng III circles of with constraint due Berwick because non-determinism. * also research Massachl;setts intelligence Agency was done of the of at is provided Department the Artificial in of Defense part by under finds the Office fol external neither IO. as the the 211. [I]. Much Instead, Laboratory of Naval is more e.g., viftua! spontaneous if it can and requires complex. It depends reasoning. no deliberative need as for Its reference In our references for syntactic inherent beyond to thus reference. ambiguous deliberation. of deliberative reference and null certain possible on the capacity lmmcdiate for incorporate arnong first incommensurate, w?tt may to discriminate ability in as the primanly of Grammar to its that of computationally of constraints. approach [6], generative complexity the scope of this Grammar derivations. Al researchers runs briefly certain structure exist transition from criticisms. rules, view modern but rather guides are the traditionat only rmplrcitly their both cbservation proposes the distinction (SI) analytic and trees Berwick approach Theory” was a tractable of TG in that light. deep-structure crucial 301. not as a annotation. “Standard Most TG as in Al [cf. deep structure in the views the traditional Chomsky’s controversial intractability a surtace-interpretive annotatIon to reconsider as follows. should advocates No longer They has remained computational mtractabte Berwick In surface created. (TG) alleged Al researchers system the [5] was to SI open that to logical of we l *Ken Haase “deliberative” Since the [15] class inclusion only bc known Research Projects vittual-copy Research contract that the class hierarchy justifies between and “spontaneous” inference. artificial laboratory’s Advdnced Immediate .* no new structure, is of a correspondence Intelligence Support and nor as the problem [I: reference a hearer Technology. [26] speakers external wherein reference. world of on reference. research N00r)14-80-C-05rX. meanings concentrates Institute external to an external intended internal This We do not discuss (private) structure. are explicit from inierences, an inference foundation system urges internal new Al and Transformational [4] argues exptrcitty Reference distinguished of terms the pragmatics analyze first no otf” They reference paper. The Russell relations reasoning contradictory. discussion below. “read creates involved references, further conceived discussed are Immediate just referential a bootstrapping preliminary immediate Both [2].* * * complex Deliberative for representations theoretical an internal Ireference: ccmplexity. We consider Transformational the non-determinism deep-structure limit to Marcus’ reference. We 161 constitutes reterence. spontaneous reference requiring referents. Hypothesis: minimizes on the conducted the range Reference, as a corollary 14, however, creating utilize deterministically, Deliberative constraints locate that [8] or reflection immediate with times [3, 121. constructions, This [13, not, do of internal computational memory, at inheritance deliberation belief-revision. We focus Research We framework constraints representations be computed reasoning syntax. of NPs dehberative or constraint-posting reference referential copy of non.monotonic work. two categories medtated distingllished simpler. eliminates hypothesis. Pragmatic of the world. public resolution reference within I Determinism capable model using of our We distifiguish analysis, conclude satisfy referenttal antecedent reference Hypothesis, non-determinism. reference. or her Marcus’ and constraint-posting deep-structure the and his of sentences important a foundational Referential that minimize reference extend reference, a sentence private on constraint-posting, This for theories at MIT-MC deep approach. based rmmed/ate explicit a semantic reference. a determinism longer non-determinism% Hypothesis of no for projection referential Determm~sm subc!ass they JCMa between would indIspensable mlnlmlze argumg linguists MA 02139 Gavan at MIT-MC, Abstract Most Science of Technology inheritance nothing can be computed to be inheritable (not quickly actually m the category we place of spontaneous inference. does not have exceptions aside from reference. [24] and default inherited), relations need our version of We assume and that the virtual inheritances operations can only suggested using relations while scopes development of could structures for Shortly thereafter, “trace theory”, find reference. p%stmg, we from SI to be less Together with the deep-structures parser* principle embodied committing to any Backtracking are parse-tree nodes are posted Both l l possible may Using implements Before The sub-divide 191. parser transformational * The Mallery. Gnoscere networks. Winston analogical reasoning f7eldtl:s trees compossd This some parts a sentence !ransformational of intelligent and semantic the tree reference creates a nodes and headed parser which feasibility HAS-TENSE HAS-ASPECT by system of a real-time network that provides PAST) PERFECT) The represented [31] showed The mechanism trees hlallery suited in bellcf close that to semantic converts with netwol ks ate representation syntxtic Gnoscele’s collaboration These system uses of a lelational defap reference structure system Research Duffy. in was on the IS still preliminary. algorithm fan outtop-down according would to the branching factor Elmer is presented reference points token list constrailit for some tree crimes in marks Figure where appiied :oblect srgnify subject and object verbs). So in Figure reference that of that takes IS being 1, the subject In the reference ..I. at the top. parallel algorithm would the bottom-most perform non-terminal reference nodes. of “fanning the constraint into” tree the sentence of ‘police’). which ‘secret’. The participates to ‘police’, ‘pokce subject-relatiorr as A subject-relation The (oblecls the constraint subject They omitted indlvrdual-p as opposed of IS is is the by the and/or designate for the the unergative the ‘police’ to an ‘Elmer’. constraint subject and thus is followed of the ‘want’ relation the State” symbol reference keywords are wanted of the place, xonsfrainfs referenced. is the reference for an individual police appearance following keyword relation secret symbol In the reference. a relation and the object are looklng from tor some the totalitarian reference The The “The against every a single composltlon. type to be referenced. of constraints committed I\lote that 1. points of semantic for the sentence that were of the deep structure. A Elmer Figure 1: Constraint tree for “The secret police wanted crimes that were committed by the totalitarian sfate. ” a constraint-posting and a set of reference contraints. It was implementgd by is built out of a frame system and implements multiple .L. bottom-up T) creates nodes. was implemented by the computational HQ 1) ((TRUE)))) T) ((TRUE) (PMSUBJECT-RELATION TRANSFORMED-BY PASSIVE-TRANSFORM (PMSUBJECT-RELATION HAS-TENSE PAST) (PMSUBJECT-RELATION HAS-ASPECT PERFECT) (SUBJECT-RELATION AGAINST (REFERENCE STATE :CONSTRAINTS ((INDIVIDUAL-P) (PNUMBER-OF-SUBJECT-RELATIONS HQ 1) (SUBJECT-RELATION HQ TOTALITARIAN ((TRUE) ))) :FORCE-NEW-P NIL :PARTICULAR-P r))))) :FORCE-NEW-P NIL :PARTICULAR-P T)))) localizing localization specialist suitable [7]. :CONSTRAINTS network. of expert of TG ((INDIVIDUAL-P) (SUBJECT-RELATICN HAS-QUANTITY PLURAL) (PMDBJECT-RELATION-TO-UNKNOWN COMMI r (RCFERENCE-UNKNOWN *SOMETHING* :CONSTRAINTS ((INDIVIDUAL-P))) of the sentence key, environment from the LF The semantic two existing of the constraint other in deep (LF). and traversal of tasks, as a match tree composed is a de!erministic, constramt A parallel tree constraints, one for each lel&onal Into of subtrees thO?lgh into phase, match of the semantic base is a semantic mechanism rmol~?rnented only depth-first respective reference form particular to a network differ ((INDIVIDUAL-P)) NIL :PARTICULAR-P ((TRUE) (PMSUBJECT-RELATION (PMSUBJECT-RELATION (SUBJECT-RELATION FOR (REFERENCE CRIME see” avoidrng depth-first in input it constrair?t parse should go to Katz [20]. knowledge tlees even for demonstratiny reference semanttc its their In the the constraint structure Credit The made a subset necessary) support any its their unwinds, The explicit logical of post recursion relationshlps independent within to VP node. constitute the constramts ELMER :CONSTRAINTS :FORCE-NEW-P :CONSTRAXNTS [25], and are tree is traversed reference a hierarchical posting Relatus “wait *** nodes. from (when nodes. deep structure deep syntactic l created phases traversed grammatical or this (REFERENCE POLICE :CONSTRAINTS ((INDIVIDUAL-P) (PNUMBER-OF-SUBJECT-RELATIONS (SUBJECT-RELATION HQ SECRET :FORCE-NEW-P NIL :PARTICULAR-P (REFERENCE :OBJECT thereby decomposes is deep-structure representation canonicalized Duffy or semantics constructed the successful be new. phase :SUBJECT explicit than analysis. decisions they When to the top-level constraints “public”, inference, base, by using to these Because the is MUMBLE is recursively. constituents (REFERENCE WANT Below, Posting of action, because the constraint to the deep-structure makes to the are relations. rather us, constraint-postmg immedtate tree attached the canonical For network. on, supervises its have knowledge we gain so of efficient between Relatus course parse-tree tree, Second, In the semantic l on constraint referenced * the generation avoided the and conserves specrailst each a constraint constraints on constraint situated constraint-posting syntax First, nodes. notwork: them from phases. a tree is available. Mapping constramts is based of constraint-posting particular We and backtracking. Using Constraint use in it appears. architecture and in sentence when full information than for computattonnlly of grammatical for our leaves structure. to dictate the efficiencres Reference before composes are surface appeared parsimonious we Illustrate telling for logical a reference general recursive In the parsimony mechanism co&traints starts. relations left 7 he sentence by constraints, began relations reference A precedent false [l l] and logical recomputation Immediate posts quantifier Fiengo by itself. scope relations indispensable for the analysis IV determining grammatical needless Relatus Below, l l level, [18] be abandoned. transformational which the surface Jackendoff of grammatical (pointers) both the grammatical they eliminate Gnoscere. which of traces deep structures examine in Interpretation be computed We level. Interpretation surface Since explicit the relations. that deep structures found for logical by the representation. at the surface structures retaining and other determined be determined deep means an l+iQ constraint to Its universal we (the class that we want a ‘police’ (has-quality) at1 ordinary means constraint. relation Ordinary to constraints inverse Only are necessary. A successful of a subject-relation relations objects have referent constraint truth value is constraints may both have quantiflcational must satisfy them. object-refalion an (e.g. constraints The true). Relations (e.g., decision-making constraint. syntactic and object un/versa/-p). told (predicate to post its individuals A P prefix constraints. These Successful order selection referents successful of preference distinguishes the PM, also use but lhey For over most example, 1 does by scheme to order the successful if the referent preference finds aiding constraints, prefixed with semantic possibility space, may node’s are constraints displaced represented instead displacement occurs pmo@ect-relation ‘crime’. raised not itself in in prepositional is explicrtly nodes exploit their posting are example, in deep structure appear reference Constraint:; laughed”, presented of the because an unspecific object for want to expltcltly. constraints positional canonical Restrictive then man . . .>). Smce embedded ‘man’. there is select by the constraint who 2, contain The was the the no to the supenor for The by the The object. the an explicit is are embedded referent Quite contrast, specialist. lf the NP scopes constraints and posts is a clause, them as referential it tells decision-making the c&se restrrctions by to pass on the noun. posting of because them in NP back its syntactic Local requiring a referent tree node. referent returns in its own the position of recomputation “access” be forced third are repeatedly) caches the forward. clearly the various not components passed would in would approach. (often off to backtrack and reasoning that of of a parse alternative approach deep be less It would add positional and parse-objects. In this information explicitly. tree without repeatedly deep any can therefore trees simplify need only parse localize factor that without full need only to retract occur in constraint-posting enough tree nodes and simplify knowledge to constraints or remember their the algorithms for and reference. of sentences has mmimlzes three representation tree will fall of the semantic transformations (e.g., for nature this further and not constituents beneftcial (belief point.* simplifies representation due to syntactic all learning). are The Since syntactically irregularities. eliminates on the The effectively it the resulting reference. operations parser First, network revision). Second, the representation to canonical effects. of the semantic backtracking above illustrate constraint and major canonical semantic In the figures reference is taken is no need to recompute because the (syntactically) reference parse structures reference canonicalizatron precludes starts There is the critical No action the constituents transformation semantic structure information case. composition before an A deterministic. ad hoc structures The the would SI read from full the canonical The 103 simply False canonical semantic Once require interpretive between Canonical thus existing node is found, a new the returned the deep-structure reference. and using reference Reference would approach reference Use constraints. by the police the references. guarantees an and in turn, structures premature form itself, The tree determines in determining is top. at any the information. immediate constraint tree, the reference than structure network constraint using trees. deliberative store itself each relationships information handle T) for chosen, efficient the deep by constituents local failure, at the references and constraints. approach forcing overhead information. exemplify the node to constituents finds of immediate constraint order-of-evaluation both clauses a new for each node. non-canonical option considerable (created canonical, Relative in a semantic to the superior an St approach of Constraint who was wanted by the node sentence If no suitable references SI possibly, and less makes “The man begins. reference constraints. of the constraint an in node representation structures the syntax, “unpacking” for no is a to the associated of reference the unpack its by the constraint to examples tree then canonlcalizo elegant S. ((1RUE) (PMSUBJECT-RELATION TRANSFORMED-BY PASSIVE-TRANSFORM) (PMSUBJECT-RELATION HAS-TENSE PAST) (PMSUEIJECT-RELATION HAS-ASPECT PERFECT)))) :FORCE-NEW-P NIL :PARTICULAR-P T) :CONSTRAINTS ((TRUE) (PMSUBJECT-RkLATION HAS-TENSE PAST) (PMSUBJECT-RELATION HAS-ASPECT PERFECT))) Figure 2: Constraint faug hed. ” phase be referenced. Determinism composition tree to the symbol structure data Whichever already 1) from the network. ((INDIVIDUAL-P)) NIL :PARTICULAR-P constitute corresponding it is returned Minimally, The (REFERENCE LAUGH :SUBJECT (REFERENCE MAN :CONSTRAINTS ((INDIVIDUAL-P) (PMDBJECT-RELATION WANT (REFERENCE POLICE :CONSTRAINTS :FORCE-NEW-P when referenced its constraints. and order intermediate ‘man’ and semantic object V police on constraints the ‘want’ of indexed constraints deep-structure head designated reference. are objects according a clauses, includes “unpack” of of an NP. transformation appropriate tree in Figure tree classness and object. any referent Only constraint non-terminal reference relative transform’s Because riced wanted is as or the reference find would may successfully (or created), including relative a restrictive VP and object on the subject referential behavior satisfies the position plan presence modifiers the parse S, to post the always the semantic of the which is found hierarchical decisions, as adjectival I’1 he for passive percolated all by definiteness constraints. up the of its one IS created CiauseS, relative structure simplified pre-determined. in Figure (<PMobject-relation internal is embcddedness, previously with symbol mechanism the relation of its Each the of uses reference grammatically a “be” its subject tree is complete constituents any extant referents !ree represented example the by virtue a unique, deep-structure easily structure. to the and the subject Whenever backtracking. working level in the trees a It iS tree. relation for all adverbs, other subsequent the restrict object occurs another, An ‘commit’ to a certain encodes Constraint trans!orm the When constraint constraints. constraint Deep of Thus, nodes. node. constraints “to be”. as constraints we must satisfies Sentence construction. Parse-tree The Any requiring created deep-structure in the resulting 1 where displacement the inter-constituent of Figure relation to a higher the raised Figure phrases. for corlstralnt-tree constraints. appear the on nodes onto It to possess Constraint directly lower to-unknown requlnng connectivity, from are node does subject. posted be displaced this of between to classify according associated network created. they specify. in the top-level and bottom-up, Constraints and its symbol for it. They it knows universals reference one this interconstraints of the verb It then adds In immediate preferring past>, nominal) Once the constraint reference. to have the feature has-tense or implementation the constraints, each [19, 221. a referent for the ‘want’ relation not have <subject-relation facilitates e.g., constraints, for the referential referent ordinary voting, candldate Preferred-mandatory others. from unweighted promising for example: the voting require need not satisfy candidates Pnumber-of-subject-re/at,ons, tICI relation constraints also constraints, any Third, need for representation compiles out syntax, makmg the semantic representation more efficient. Constraint-posting within Consider wanted man” man”. The in the sentence embodded S, The with ‘want’ relation the (e.g., would be resul!. see every whether versa. The a factor The it has repeatedly treated been of the size steeper as would size is units increases an SI [7]. in export alternative vice reduced force of syntax are emerge. reference constramts. chores our would do At the be forced or be forced Alternatively, it component. may Because on the semantic objection a mere to semantics claims to the semantic actlvitles, From approach to deep-structure, addltional Canonicalization by manipulated. be paid semantic component. structures enhances referential the of component to it is concomitantly reference, and The network A variant remam of the can rely of SI which be invented, deep deep of maximize the amount of in the necessary of the referential relations the and composltion turn, minimizing in surface of the in (belief-revision) structure may someday no longer consistency of both efficiency thereby grammatical better. enhances constraints, bzcktraskmg representation SI would input representation elegance in the semantic perform its These component. operations T) of Explicit constramts. canonicalized thus constramts structure. inherit Inference on that cnnonlcalization supports a canonical but the parsimony and semantic argument for tenable. Acknowledgements (REFERENCE ELMER :CONSTRAINTS :FORCE-NEW-P ((INDIVIDUAL-P)) NIL :PARTICULAR-P (PMSUEJECT-RELATION IPMSUBJECT-RELATION :FORtE-NEW-P :CONSTRAINTS NIL :CONSTRAINTS paper was Bob Berwick. Improved Carl provided arguments course, with remains [l] Bach, Acts. :PARTICULAR-P PAST) PERFECT)))) [2] Satall, T) HAS-TENSE HAS-ASPECT K. for “Elmer PAST) PERFECT))) [3] HAS-TENSE PAST) HAS-ASPECT PERFECT) HQ THEN NIL))) knew then Steve and Robert Bagley, Rick John Lathmp. tngria helped Responsiblllty for f3atali, Margaret refine the our content, of the authors. and R. M. tiarnlsh, Mass.: MIT Laboratory, Hawdell, A., D. Introspection.” tilllls, Memo Mass.. and MIT and Speech 1979. Cambridge, seminar, Commumcatio/l L,nguist/c Press, D. A. Artificial No. 701, February MIT Artificial 1983. McAllester, Intelligence “Virtual Copy Laboratory, Spring, 1982. [5] Chomsky, Press, View.” Aspects N., Grammar Cc)gn/t/o1I and of 6ra/l, the Theory and Theory. of Syntax. Arttficlal Intelligence: 6:4 (1983) Cambridge, 383-416. Mass.: MIT 1965. [6] Chomsky, Conclusions “Transformational R. C., that he was the wanted man. ” VII comments. comments. J. “Computational lntelltgence [4] Berwick, tree from Isaacson, detailed Cambridge, A Contemporary Constraint Joel valuable with CompressIon.” ((TRUE) (PMSUBJECT-RELATION (PMSUBJECT-RELATION (SUBJECT-RELATION by comments Hewitt, References HAS-TENSE HAS-ASPECT ((TRUE) (PMSUBJECT-RELATION IPMSUBJECT-RELATION This Fleck T) (REFERENCE MAN :CONSTRAINTS ((INDIVIDUAL-P) (PMOBJECT-RELATION-TO-UNKNOWN WANT (REFERENCE-UNKNOWN *SOMETHING* :CONSTRAINTS ((INDIVIDUAL-P))) ((TRUE) 3: relationships principle, more strenuous. the :OBJECT Figure from In analysis. SI to parsimony constraint-posting i[s ail reasoning determinism ((INDIVIDUAL-P)) NIL :PARTICULAR-P impossible, the mapping computation would slow semantic :OBJECT (REFERENCE BE :SUBJECT with the and relevant Its non-canonicalities non-deterministic (REFERENCE ELMER :CONSTRAINTS :FORCE-NEW-P when not to sentence approach Only parser is approach to -- on each reference. (REFERENCE KNOW :SUBJECT SI our recompute backtrack this an of ccmputatlons least, and thus would and must variants to variation and notational to repeatedly properties a relation, be further standpoint, simply reference of syntactic very this termed inefficiency context the full set 1 and 2.’ If, as for syntactic of the semantic as application that need to be checked expressed resources an ‘want’ relation as one-place would into are ordmarily a significant “the the wanted expanded discovers to control each property the NP he was of the in what consequsntly, is a function becomes been as that of Figures 2) were of effective that has successfully measures previously 3 for then the subject and participles Figure and knew ‘want’ relation reference, avallabilrty which cost that is treated, required. For in Figure ‘wanted’, mechanism adjectives constructs “Elmer proviso IS the same as any adjective presented adjective, constraint particlpial passive just constramts partlcipial unknown. in [4], the the N., Lectures on Government and Binding. Dordrecht: Foris, 1981. V/e have constramt.posting reference: a central how to aspect on reasoning, and thus Immediate any of increases deep improve of Canonicallzatlon semantics. deterministic, build i!lustrated reference strtictures the interlace syntax makes the efficiency reference, combine cfflclency including of between with [7] immediate syntax immediate reference of all operations deliberative and which Chomsky, Review [O] Doyle, J., A dissel reference, t&on. Some sources lngria “On 1 :l the Model MIT. Representation (1981-82) of Form and Function.” The 3-40. for [>e!iberalion, Action, and lntros;pection. Doctoral May 1980. and learning. [3] Duffy, l N. 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