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<?xml version="1.0" standalone="yes"?> <Paper uid="E93-1026"> <Title>Inheriting Verb Alternations</Title> <Section position="4" start_page="214" end_page="215" type="metho"> <SectionTitle> 2 An HPSG-style lexicon </SectionTitle> <Paragraph position="0"> The alternations to be addressed in detail here are the ones relating the transitive, which we treat as the base form, to the ergative (&quot;The cake baked&quot;) and to the unspecified object (&quot;John baked&quot;).</Paragraph> <Paragraph position="1"> Fig. 2 shows a simplified version of the HPSG lexical entry for transitive bake, in attribute-value matrix (AVM) notation. NP abbreviations and anglebracket list notation, where a comma separates list elements and there is no separator between the coni uncts of a feature-structure within a list, is as in Pollard and Sag, 1987\]. The boxed variables indicate the roles the semantic arguments play in the syntactic structure.</Paragraph> <Paragraph position="2"> For ergative bake, the same BAKE relation holds as in the base form, but now between an unspecified BAKER and a BAKED which is the subject of the sentence. The unspecified role filler is not 'bound' to a complement (i.e. any item on the SUBCAT list) but is existentially quantified (EX-Q). The ergative form is intransitive so has only one item on its SUBCAT list and the SEM of that item unifies with the BAKED, so the AVM for ergative bake will be as in Fig. 3. For unspecified-object bake in &quot;John was baking&quot;, the subject is matched to the BAKER and it is the BAKED which is unspecified, so existentially quantified, as in Fig. 4.</Paragraph> <Paragraph position="3"> For bake and other cooking verbs, we are able to represent the extended senses directly in terms of the same predicate that applied in the base sense. We now move on to a case where this does not hold.</Paragraph> <Paragraph position="4"> For melt, the intransitive (&quot;The ice melted&quot;) is basic and the transitive (&quot;Maria melted the ice&quot;) is extended, and it is not possible to define the extended sense directly in terms of the base. The transitive can be paraphrased using cause, &quot;Maria caused the ice to melt&quot; and we call the alternation 'causative'. It is clearly closely related to the ergative, and it would be possible to treat the transitive form as basic, with the ergative alternation applying. That route has not been followed for two reasons. Firstly, melt is a member of a class of physical-process verbs, also including evaporate, freeze, dissolve, sublime and coalesce. They all clearly have intransitive senses. They all might, in the right setting, be used transitively, but in cases such as coalesce the transitive is not a standard use and it would patently be inappropriate for it to be treated as a base form. If we are to stand by the intuition that these verbs form a class, and all participate in the same alternation, then all must have an intransitive base form.</Paragraph> <Paragraph position="5"> Secondly, transitive melt introduces an aspect of meaning, call it CAUSE, which is not in any sense present in the intransitive. For bake, CAUSE is already a component of the meaning, whether or not the verb is being used ergatively. A default entailment of CAUSE is that its first argument, the CAUSER, has proto-agent properties \[Dowty, 1991\].</Paragraph> <Paragraph position="6"> If intransitive melt were treated like ergative bake, CAUSE would be a component of the meaning of intransitive melt. Its semantics would have an existentially quantified MELTER argument, which would he a CAUSER and which we would expect to have agent-like properties. Ifi ergative uses of bake, the baking scenario still includes an agent who is doing the baking and fills the BAKER role, even though they are not mentioned. (We concern ourselves here only with cooking bake, not '~rhe stones baked in the sun&quot; and other usage-types where bake is behaving as a physical process verb.) In 'degthe ice melted&quot; there is usually no agent involved. While it might always be possible to assign a filler to the MELTER slot, perhaps &quot;the hot temperature&quot; or &quot;the warm climate&quot;, they do not fit readily into the agent, CAUSER role.</Paragraph> <Paragraph position="7"> So we do not treat causatives as ergatives.</Paragraph> <Paragraph position="8"> A standard analysis of causatives after \[Dowty, 1979\] as presented by \[Chierchia and McConnell-Ginet, 1990, chapter 8\], is</Paragraph> <Paragraph position="10"> The semantics of the causative has the predicate CAUSE, with MELT/1 re-appearing as its second argument. In addition to intransitive melt as shown in Fig. 5 we have causative melt as shown in Fig. 6. (The relation between lambda expressions and feature structures is discussed in \[Moore, 1989;</Paragraph> </Section> <Section position="5" start_page="215" end_page="216" type="metho"> <SectionTitle> 3 DATR: a gentle introduction </SectionTitle> <Paragraph position="0"> A simple DATR equation has, on its lhs, a node and a path, and, on its rhs, either a value: Nodel:<a b c> Iffi value.</Paragraph> <Paragraph position="1"> or an inheritance specification. Nodes start with capital letters, paths are sequences enclosed in anglebrackets, anything on the rhs that is not a node or a path is a value. The primary operation on a DATR description is the evaluation of a query, that is, the determination of a value associated with a given path at a given node. Where a value is not given directly, it may be inherited by following a trail: the inheritance specification on the dis at step n becomes the lhs for step a-/-l. The specifications may state both node and path, node only or path only. They may also be local or global. Where they are local, the unstated node or path is as it was on the lhs, so if we have the node: (Where a number of node-path specifications for a given node are stated together, the node need not be re-iterated. The full stop is delimiter for either a single equation or such a cluster of equations.) Where inheritance specifications are global, with the node or path on the rhs in double quotes: Node4: <a> -- &quot;NodeS&quot; <b) Im &quot;<Z>&quot;.</Paragraph> <Paragraph position="2"> then the 'global context' node or path is picked up to complete the specification. For the purposes of this paper, the global context node and path are the initial query node and path.</Paragraph> <Paragraph position="3"> When there is no lhs to exactly match a node-path pair to be evaluated, the mechanism which gives rise to DATR's nonmonotonicity comes into play. This is the 'longest leading subpath' principle. The node-path pair inherits according to the equation at the node which matches the longest leading subpath.</Paragraph> <Paragraph position="4"> Thus, with Node1 as defined above, then these inheritances would be overridden. Note that the match must be with the longest leading subpath. In this fragment, the queries</Paragraph> <Paragraph position="6"> all fail to match and are undefined. (The other queries may also be undefined, if the trail of inheritance specifications terminates without reaching a value at some later stage, but they are not found to be undefined at this stage.) Two particular cases of inheritance used in the pa-</Paragraph> <Paragraph position="8"> In the first, the leading subpath to be matched is null, so this is a default of defaults: no queries will terminate at this point, since any query which does not make a more specific match will match this line and get passed on from Node5 to }lode6, path unchanged. This is the simplest form of inheritance, usually used to specify the basic taxonomy in a DATR theory. In the second, path element e is 'chopped' from the beginning of the path, so:</Paragraph> <Paragraph position="10"/> </Section> <Section position="6" start_page="216" end_page="216" type="metho"> <SectionTitle> 4 Translations into DATR </SectionTitle> <Paragraph position="0"> Now we move on from describing the alternations, and describing the inheritance formalism, to representing the alternations within the formalism. The DATR translation is straightforward: AVMs can be rewritten as sets of equations which then become sets of DATR equations. DATR paths must be associated with nodes, so a node for the paths to be located at is introduced. FIRST and REST have been shortened to fi and re. DATR is not a unification formalism, and all the theory will do in relation to re-entrancies will be to mark them with matched pairs of variables, here vl, v2 etc., to be interpreted as re-entrant pairs outside DATR. We introduce the feature binding for the variables to be the value of. 2 In order that generalisations covering BAKERs, COOKERs and FRY-ERs can be stated, we replace verb-specific names such as BAKER for slots on a semantic args list.</Paragraph> <Paragraph position="1"> (This does not represent a change in the semantics: the first member of the argument list of the bake predicate will continue to be the BAKER whatever lexical entry it occurs in. It simply allows us to express generalisations.) We use pred for the predicate rather than RELN. Following these changes, the (simplified) DATR lexical entry for transitive bake is: Bake : <word> = bake <syn maj> = v <syn subcat fi sem binding> = vl <syn subcat re fi sem binding> = v2 <syn subcat re re> = nil <sem pred> = bake a semantic argument has an existential-quantification (ex-q) binding to override the default that it is bound to a complement.</Paragraph> <Paragraph position="2"> <sere args re fi binding> = v2 <sem args fi binding> ffi nil.</Paragraph> </Section> <Section position="7" start_page="216" end_page="218" type="metho"> <SectionTitle> 5 An inheritance hierarchy </SectionTitle> <Paragraph position="0"> The next task is to place the verbs in a hierarchy so generalisations need stating only once. DATR allows different kinds of information to be inherited from different places, and also allows generalisations to be overridden by either idiosyncratic facts or subregularities. The hierarchy is illustrated in Fig. 1. At the top of the tree is WORD-CLASS, then VERB, from where all verbs inherit. They all have a subject, and by default this unifies with the first item on the axgs list. There will be no call for an INTRANSITIVE node because all the positive information that might be stated there is true of all verbs so can be stated at the VERB node, and the negative information that intransitive verbs do not have direct objects is expressed by the termination of the subcat list after its first item at VERB (via ARG and NIL; see below).</Paragraph> <Paragraph position="1"> <sere args re fi binding> == v2.</Paragraph> <Paragraph position="2"> List termination involves a measure of ingenuity, in order that nil is the value of <syn subzat re> and <sem args re> at VERB and <syn subcat re re> and <sere args re re> at TRANSITIVE, but nowhere else: 3 The COMP and ARG nodes provide a location for default information about syntactic complements and semantic arguments. Complements are, by default, accusative noun phrases. Following \[Dowry, 1991\], we have a default expectation that subjects will have 'proto-agent' semantic features and objects, 'protopatient' ones. The role of Dowty's approach in this analysis is that it gives us a way of marking the difference between agents and patients which says more than simply using the labels 'agent' and 'patient', and has the potential for subtler distinctions, with different subsets of proto-agent and proto-patient features applying to subjects and objects of different verb classes. AGENT and PATIENT set up the expected values for four of the characteristics Dowty discusses.</Paragraph> <Paragraph position="4"> The default accusative case and proto-patient semantic features must be overridden in the case of the subject: VERB:<syn subcat fi syn case> == nom <sam args fi semfeats> == AGENT:<>.</Paragraph> <Paragraph position="5"> To this skeleton, we add some smaller classes based on meanings. Once we introduce them we can start expressing generalisations about alternation behaviour. To distinguish alternate forms from base forms, we introduce the alt prefix. To request information about a non-base form, we start the query path with alt x, where x is a label identifying the alternation under consideration. We adopt a convention whereby all-upper-case nodenames are used for nodes for classes of words, such as cooking verbs, while lexical nodes have only initial letters</Paragraph> <Paragraph position="7"> <alt erg sam> =ffi &quot;<sere>&quot; <alt erg sam args fi binding> == ex-q <alt erg sam args re fi binding> ffi vl.</Paragraph> <Paragraph position="8"> Bake is a cooking verb, and cooking verbs are, in the base case, transitive change-of-state verbs. Thus Bake inherits, by default, from C00KING-VB which inherits from C-0F-S (for 'change of state') and then from TRANSITIVE, so acquiring the default specifications for semantic features for its subject and object, and the re-entrancies between subject and first argument, and object and second argument. The DATR fragment now represents all the information in the DATR lexical entry for bake presented above, and case and proto-agent and proto-patient specifications in addition.</Paragraph> <Paragraph position="9"> The first generalisation about alternations that we wish to capture is that change-of-state transitives such as bake undergo the ergative alternation to become change-of-state intransitives, or 'physical process' verbs. We access the lexical entries for the ergative forms of verbs with DATR queries with the path prefix alt erg, which work as follows. The semantics of the ergative will be the same predicate-argument structure as the base form, and this is implemented in the third line of the C/-0F-S node which tells us, with the double-quotes, to inherit the ergative's semantics from the semantics of the node for the base form of the verb. The two further specifications for ergatives are that the first argument is existentially quantified, and the second unifies with the first complement via vl.</Paragraph> <Paragraph position="10"> In all other matters, as the second line of the C-0F-S node tells us, the ergative form is diverted to inherit from a node for physical-process intransitives: null</Paragraph> <Paragraph position="12"> The first semantic argument of a physical-process intransitive has proto-patient semantic features and otherwise inherits from VERB. This is a case where the default - that first semantic arguments (realised as subjects in the base case) have proto-agent features - has been overridden, but the reader will note that this has been entirely straightforward to express in DATR.</Paragraph> <Paragraph position="13"> We now have almost all the information needed to build the lexical entry for ergative bake. One item we do not yet have is the intuitively obvious fact that the word for the alternate form is the word for the original. This is true by definition for all alternate forms. All alternate forms will eventually have their alt x prefix (or prefixes) stripped and inherit from WORD-CLASS at the top of the tree. So we add the following line: NORD-CLASS:<word> == &quot;<word>&quot;.</Paragraph> <Paragraph position="14"> Now all alternate forms will inherit their .ord from the word at the global context node, which will always be the node for the base form.</Paragraph> <Paragraph position="15"> Many cooking verbs undergo the 'unspecified object' alternation, for which we shall use the label unspeC/. All information relating to this form is gathered at an UNSPEC node: UNSPEC: <> == VERB <sam> == &quot;<sam>&quot; <sam args re fi binding> :ffi ex-q.</Paragraph> <Paragraph position="16"> This simply states that the form is a standard intransitive, with the semantics of the base form except that the second argument is existentially quantified. Cooking verbs with alt unspec prefixes are diverted here by the addition of: C00KING-VB:<alt unspec> ffi UNSPEC:<>.</Paragraph> <Paragraph position="17"> Now we move on to melt, a physical-process verb with a causative form. The ergative alternation led from C-0F-S to PIIYS-PROC. This makes a similar journey in the opposite direction, from PIIYS-PROC to CAUSE and then TRANSITIVE. The alternation label is cause.</Paragraph> <Paragraph position="18"> Causative melt, with the alt cause prefix, is a regular verb of causing, and inherits its syntax and most of its semantics including the predicate cause/2 from CAUSE. Its first argument will have the usual characteristics of a CAUSER, and its second, the predicate-argument structure of the base form of the verb. As the predicate melt is now identified as the second argument of cause, the item that melts is identified as the first argument of the second argument of the causative form of the verb, and it is this which is re-entrant with the second item on the subcat list, as specified in the final line of PHYS-PR0C. The reward for this superstructure is that lexical entries can now be very concise. By adding a three- null line entry, e.g., Bake: <> == COOKING-VB <gord> == bake <sem pred> == bake.</Paragraph> <Paragraph position="19"> to the lexicon, we make available, for cooking verbs such as bake, a set of eighteen specifications for the base form, and fifteen each for the ergative and unspecified-object, and for physical process verbs, fifteen for the base and eighteen for the causative, all</Paragraph> <Paragraph position="21"> re fi syn ~aj> = n.</Paragraph> <Paragraph position="22"> re fi syn case> =acc.</Paragraph> <Paragraph position="23"> re fi sem binding> - v2. subcat re re> = nil.</Paragraph> <Paragraph position="24"> pred> = bake /2.</Paragraph> <Paragraph position="25"> args fi binding> = vl.</Paragraph> </Section> class="xml-element"></Paper>