Semantic roles and Grammatical Relations
المؤلف:
PAUL R. KROEGER
المصدر:
Analyzing Grammar An Introduction
الجزء والصفحة:
P51-C4
2025-12-12
35
Semantic roles and Grammatical Relations
The Phrase Structure model is a very useful tool for analyzing sentences. However, as we will see here, Phrase Structure rules by themselves cannot provide an adequate account of what speakers say. For example, the simple set of Phrase Structure rules can produce odd sentences like those in (1) and (2).
(1) a #The young sausage likes the white dog.
b #Mary sings a white cake.
c #Asmall dog gives Mary to the young tree.
(2) a *John likes.
b *Mary gives the young boy.
c *The girl yawns Mary.
Even though the rules seem consistent with what we know about the grammar of English, we see that they can produce unacceptable sentences. These sentences are unacceptable for different reasons. The # sign before the sentences in (1) indicates that they are semantically ill-formed, i.e. they cannot be given an acceptable semantic interpretation. The * sign before the sentences in (2) indicates that they are ungrammatical. In (2a, b) we feel there is a phrase missing, while (2c) seems to contain an extra phrase.
We will discuss these problems in detail in Lexical entries and well-formed clauses. For now the important point is that even though the Phrase Structure rules themselves may be correct, this will not necessarily ensure that the output of the rules is grammatical. Additional information is needed, information about the specific words which are used. This kind of information must be stored in the lexicon in some way.
Another type of complication that can arise is illustrated in (3). The PS rules could generate this sentence in two different ways. This means that the rules assign more than one possible Phrase Structure for this sentence, as shown by the two tree diagrams in (4). These two structures correspond to two different interpretations of the sentence. Can you identify the meanings which would be associated with these two structures?
(3) John pinches the young girl behind the tree.
The sentence in (3) is an example of STRUCTURAL AMBIGUITY; the sentence as a whole is ambiguous because it has two possible Phrase Structures, even though none of the individual words is ambiguous in this context.1 Is it some problem with our PS rules that allows the same sentence to be assigned two different structures in this way? Not at all. This is simply a fact about English grammar. Sentence (3) really is ambiguous, so it is actually a good thing that our PS rules generate both of the structures shown in (4).
In providing two analyses for (3), our miniature rule system is successful in the sense that it produces the same results as a native speaker’s internal grammar. In contrast, when the rules produce sentences like those in (1) and (2) they are clearly failing to model what speakers actually say. In order to fix these problems we need to consider the unique properties of individual words, in particular of verbs. We will also need to refer to two aspects of sentence structure we have not yet discussed, namely SEMANTIC ROLES and GRAMMATICAL RELATIONS. We will begin this discussion by considering certain aspects of word and sentence meanings.
1. In (4a) the PP is an adjunct describing the location of the event, while in (4b) the PP is a modifier indicating which girl was involved.
الاكثر قراءة في Semantics
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