Day 4: HPSG approaches to information structure The signature of an HPSG grammar The signature • HPSG in a nutshell • defines the ontology (‘declaration of what exists’): • Approaches to information structure: – which kind of objects are distinguished, and – Engdahl and Vallduv´ ı (1996) and Engdahl (1999) – which properties of which objects are modelled. – De Kuthy (2002) and De Kuthy and Meurers (2003) • consists of • Issues for future work and discussion – the type hierarchy (or sort hierarchy) and – the appropriateness conditions , defining which type has which appropriate attributes (or features) with which appropriate values. 1/68 HPSG in a nutshell 3/68 HPSG in a nutshell Descriptions An HPSG grammar formally consists of A description language and its abbreviating AVM notation is used to talk about sets of objects. Descriptions consists of three building blocks: I. the signature as declaration of the domain, and II. the theory constraining the domain. • Type decriptions single out all objects of a particular type, e.g., word The theory, from a linguistic perspective, consists of • Attribute-value pairs describe objects that have a particular property. The attribute must be appropriate for the particular type of object, and the value a) a lexicon : licensing basic words � � � name mary � can be any kind of description, e.g., spouse b) lexical rules : licensing derived words • Tags (structure sharing) to specify token identity , e.g. 1 c) immediate dominance (ID) schemata : licensing constituent structure d) linear precedence (LP) statements : constraining word order Complex descriptions are obtained through conjunction ( ∧ ), disjunction ( ∨ ) and e) a set of grammatical principles : expressing generalizations about negation ( ¬ ). In the AVM notation, conjunction is implicit. linguistic objects HPSG in a nutshell 2/68 HPSG in a nutshell 4/68
ÿ ÿ ÿ The theory of an HPSG grammar Example lexicon A theory is a set of description language statements, often referred to as the 2 phon < drinks > 3 ů verb 2 3 2 3 6 7 constraints. head 6 7 vform fin 6 7 6 cat 7 6 7 6 7 6 7 4 5 word → D E ∨ • The theory singles out a subset of the objects declared in the signature, 6 7 6 NP[ nom ] 1[ third,sing ] , NP[ acc ] 2 7 subcat 6 6 7 7 synsem | loc 6 6 7 7 namely those which are grammatical. 2 3 6 6 drink’ 7 7 6 6 7 7 6 6 cont drinker 7 7 1 4 4 4 5 5 5 • A linguistic object is admissible with respect to a theory iff it satisfies each of drunken 2 the descriptions in the theory and so does each of its substructures. 2 phon < she > 3 ů noun 2 2 3 3 6 7 4 head Note that HPSG models linguistic objects, i.e., total objects as they exist in the 6 7 cat case nom 6 6 6 7 7 7 ∨ 6 6 5 7 7 world, not potentially partial knowledge about the world. Every linguistic object 6 6 subcat �� 7 7 synsem | loc 6 6 7 7 ů per third 6 6 " ÿ # 7 7 thus is total with respect to the ontology declared in the signature. Formally, the 6 6 7 7 cont index 4 4 5 5 num sing feature structures used as models are required to be 2 3 – totally well-typed : Every node has all the attributes appropriate for its type phon < wine > ů head 2 3 6 noun 7 and each attributes has an appropriate value. 6 cat 7 subcat �� 6 7 6 7 – sort-resolved : Every node is of a maximally specific type. 6 ů per third 7 synsem | loc 6 7 " ÿ # 6 7 6 7 6 7 4 cont index 5 4 5 num sing HPSG in a nutshell 5/68 HPSG in a nutshell 7/68 Sketch of an example analysis Immediate Dominance Principle (for English): 2 3 2 à " # ! 3 verb � � 4 head ∨ ¬ verb � head 3 � 6 7 synsem | loc | cat inv − 6 7 synsem | loc | cat 6 7 5 subcat �� 6 7 " # subcat �� 6 7 phrase 6 7 → (Head-Subj.) 2 3 6 7 dtrs headed-struc head-comp-struc 6 7 s h 6 7 head-dtr phrase 6 7 6 dtrs 7 6 7 6 7 D E 4 5 4 comp-dtrs 5 � phon < she > � sign � � � � head 3 synsem 1 synsem | loc | cat � � subcat 1 2 3 2 à " # ! 3 verb head ∨ ¬ verb 6 7 6 inv − 7 synsem | loc | cat 6 7 h c 6 7 6 7 4 5 D E ∨ 6 7 subcat (Head-Comp.) synsem 6 7 6 7 phon < drinks > � phon < wine > � " # 6 7 head-comps-struc 6 7 dtrs synsem 2 � verb � 4 5 head-dtr word head 3 synsem | loc | cat vform fin � � subcat 1 , 2 ∨ . . . . . . HPSG in a nutshell 6/68 HPSG in a nutshell 8/68
The interface between prosody and information structure An example principle: The Head-Feature Principle (HFP) • Following Bolinger (1958), Engdahl and Vallduv´ ı assume that focus and link (topic) are each marked by a pitch accent: A accent (falling contour) and B accent (fall-rise). • The connection between intonation and information structure is expressed in � phrase � � synsem | loc | cat | head � 1 → HPSG by extending the phon value with a feature accent and specifying: dtrs headed-structure dtrs | head-dtr | synsem | loc | cat | head 1 2 3 phon | accent A " # word → 5 ∨ content 6 7 1 synsem | loc 4 context | info-struc | focus 1 2 3 phon | accent B " # 5 ∨ content 6 7 1 synsem | loc 4 context | info-struc | ground | link 1 2 3 phon | accent unaccented " # content content 6 7 synsem | loc 4 5 context | info-struc info-struc HPSG in a nutshell 9/68 11/68 The approach to information structure of Engdahl and Vallduv´ ı An example analysis: Narrow object focus S fin 2 2 3 3 focus • The approach of Engdahl and Vallduv´ ı (1996) is built on the information 1 " # 4 synsem | loc | context | info-struct link 4 packaging theory of Vallduv´ ı (1992), and they assume the same partitioning of 6 6 7 7 ground 4 5 5 tail focus and ground , with the ground further divided into link and tail . 2 • Engdahl (1999) encodes this approach by enriching HPSG signs with the NP nom VP fin following information structure representation: 2 3 2 2 3 3 phon | accent B content 3 " # " # content 4 4 s | l focus 1 6 7 6 6 7 7 s | l 4 5 cxt | info-struct 2 3 4 5 5 sign cxt | info-struct | ground | link 4 ground | tail 2 2 3 2 3 focus content 6 7 6 7 6 " # 7 6 7 synsem | local | context 4 info-struc link content 6 7 John 6 7 6 7 ground 4 5 4 5 V fin NP acc 5 tail content " # 2 3 phon | accent A phon | accent u " # s | l | content 2 content 1 6 7 s | l 4 5 cxt | info-struct | focus 1 plays RUGBY The approach of Engdahl and Vallduv´ ı (1996) 10/68 The approach of Engdahl and Vallduv´ ı (1996) 12/68
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