this completes the
process of generating the sentence. A tree structure like (12), which matches
the actual sentences we are trying to produce, is called its SURFACE STRUCTURE.
Inflectional
spellout rules
To get from (11) to (12), we need one
rule that adds –z to the end of any noun that is [+plural] and another that
adds –d to the end of any verb that is [+past]. We call these rules
INFLECTIONAL SPELLOUT RULES and write them as follows:
(13) Inflectional spellout rules for noun
plurals
N
[+plural]
[X] à [Xz]
(14) Inflectional spellout rules for past tense
on verbs
V
[+past]
[X] à [Xd]
Other features are more limited in their
distribution. For example, [+plural] can only be allowed to appear on certain
nouns. Other nouns, like software do not have plural forms (i.e., *softwares is
not a grammatical English word). This latter group is called mass nouns. This
means, before we can talk about plural forms of nouns, we must first divide the
class of nouns into two subcategories in the lexicon, using the features [+count]
and [-count].
(17) N [+count] N
[-count]
sændwIt∫ sandwich sænd sand
kƏm`pju:tƏr computer softweƏr software
when a noun is inserted in a tree, we assume it
carries with it all the features that it has associated with it in the lexicon
(although we don’t usually write all of them). So every N node in every tree
ends up with a feature for [count].
Irregular inflectional in formal Grammars
In every language, there are words that
are INFLECTED IRREGULARLY, that is, which have some forms that do not follow
the regular inflectional rules. These irregular, or SUPPLETIVE, forms must be
listed in the lexicon, since they are not predictable by rule and must be
learned individually. For example, the lexical entry of go might look like this:
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