Ergatives

Verbs in English that we will callergative ^7.1 display the kind of alternation shown in the sentences in ((7)) and ((8)) below.

(6)0(6

(7)

The sun melted the ice .  (7)0(7

(8)

The ice melted . 

The object of the transitive sentence in ((7)) corresponds to the subject of the intransitive sentence in ((8)). The literature discussing such pairs is based largely on syntactic models that involve movement, particularly GB. Within that framework two basic approaches are discussed:

• Derived Intransitive
  The intransitive member of the ergative pair is derived through processes of movement and deletion from an underlying transitive structure [#!Burzio86!#,#!HaleKeyser86!#,#!HaleKeyser87!#].
• Pure Intransitive
  The intransitive member is intransitive at all levels of the syntax and the lexicon and is not related to the transitive member syntactically or lexically [#!Napoli88!#].

Although XTAG does not have derivational movement, the relationships between the two arguments can be translated to the FB-LTAG framework. In the XTAG grammar the difference between these two approaches is not a matter of movement but rather a question of tree family selection. The relation between sentences represented in terms of movement in other frameworks is represented in XTAG by membership in the same tree family or selection of multiple families which preserve the argument relations across families. Wh-questions and their indicative counterparts are one example of the former, whereas ergatives and ditransitives with PP shift exemplify the latter. Adopting the Pure Intransitive approach suggested by [#!Napoli88!#] would mean placing the intransitive ergatives in a tree family with other intransitive verbs and separate from the transitive variants of the same verbs. This would result in a grammar that represented intransitive ergatives as more closely related to other intransitives than to their transitive counterparts. The only hint of the relation between the intransitive ergatives and the transitive ergatives would be that ergative verbs would select both tree families. While this is a workable solution, it is an unattractive one for the English XTAG grammar because semantic coherence is lost. In particular, constancy in thematic role is represented by constancy in node names across sentence types within a tree family. For example, if the object of a declarative tree is NP₁ the subject of the passive tree(s) in that family will also be NP₁. The analysis that has been implemented in the English XTAG grammar is an adaptation of the Derived Intransitive approach. The ergatives select the two families Tnx0Vnx1 and TEnx1V. TEnx1V is quite similar to the regular intransitive family Tnx0V, except that it encodes a different type of semantic function--the syntactic subject of TEnx1V is given the index of `1' to represent that it is the logical object of the verb. The two families Tnx0Vnx1 and TEnx1V create the two possibilities needed to account for the data.

• intransitive ergative/transitive alternation. These verbs have transitive and intransitive variants as shown in sentences ((9)) and ((10)).

  (8)0(8

  (9)

  The sun melted the ice .  (9)0(9

  (10)

  The ice melted . 

  In the English XTAG grammar, verbs with this behavior select family {Tnx0Vnx1 TEnx1V}. The first family in the union handles sentences such as ((9)) and the second covers ((10)).

• transitive only. Verbs of this type do not allow the intransitive ergative variants, as can be seen in the pattern shown in sentences ((11)) and ((12)).

  (10)0(10

  (11)

  Elmo borrowed a book .  (11)0(11

  (12)

  A book borrowed . 

  Such verbs select only the family Tnx0Vnx1, and thus do not have the ergative trees in TEnx1V available to them.

{Ergative Tree: $\alpha$Enx1V

   

The declarative ergative tree is shown in Figure 7.1. Note that the index of the subject NP indicates that it originated as the object of the verb.