Editing Lexical semantics (section)

=== Intransitive verbs: unaccusative versus unergative ===
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| image1 = Unaccusativeexample.png
|thumb
| caption1 = Underlying tree structure for (2a)

| image2 = Unergativeexample.png
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| caption2 = Underlying tree structure for (2b)

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The unaccusative hypothesis was put forward by David Perlmutter in 1987, and describes how two classes of intransitive verbs have two different syntactic structures. These are [[unaccusative verb]]s and [[unergative verb]]s.<ref name="Lappin">Lappin, S. (Ed.). (1996). Handbook of contemporary semantic theory. Oxford, UK: Blackwell Publishers.</ref> These classes of verbs are defined by Perlmutter only in syntactic terms. They have the following structures underlyingly:

* unaccusative verb: __ [<sub>VP</sub> V NP]<ref name="Lappin" />
* unergative verb: NP [<sub>VP</sub> V]

The following is an example from English:

{|
|-
|  
 (2) '''Unaccusative'''
     a. ''Mary fell.''<ref>Loporcaro, M. (2003). The Unaccusative Hypothesis and participial absolutes in Italian: Perlmutter’s generalization revised. Rivista di Linguistica/Italian Journal of Linguistics, 15, 199-263.</ref>
     '''Unergative'''
     b. ''Mary worked.''
|}

In (2a) the verb underlyingly takes a direct object, while in (2b) the verb underlyingly takes a subject.