Assume, for the moment, a conventional phonological framework in which all lexical entries are defined as having a phonological structure consisting of sequences of structured syllables, a syllable consisting of an onset (the initial consonant cluster), a peak (the vowel(s)) and a coda (the final consonant cluster). Such a structure can be defined at the top of a (phonological) hierarchy, and will apply, by default, to all words attached to that hierarchy. In such a lexicon structure, individual lexical entries do not need to specify the phonological structure itself but just the values of the relevant onsets, peaks and codas.
Assume also a rather traditional morphological framework in which all lexical entries are defined to have a morphological structure consisting of a stem together with zero or more affixes. For English and German, such a morphotactics would specify a stem and a single suffix as the default. As in the case of default phonological structure, this can be stated at the top of a (morphological) hierarchy. Since the inheritance of lexical information is best treated as nonmonotonic, these general structural definitions can be overridden at any point lower down in the hierarchy. An example hierarchy for an English lexicon is shown below.
Here, abstract (non-terminal) nodes are marked with solid boxes, with concrete (terminal) lexical entries marked with dashed boxes. In this example of a morphological hierarchy, we can see that nouns, verbs, adjectives, and so on, all inherit from Word. Below the Verb node, we have a mix of terminal and non-terminal nodes, with regular verbs such as ask and talk inheriting directly from Verb and sub-regular verbs, such as bring and swim inheriting from Verb_A and Verb_B nodes respectively. Thus alternation information common to a class of subregular verbs will be defined at the node for that class, with the verbs belonging to the class inheriting from it. For example, the past tense peak of Verb_A verbs is always /O:/and so this can be inherited from the Verb_A node, rather than being specified separately at each individual verb entry.
This type of inheritance network can be applied to all forms of lexical description, including orthography, phonology, morphology, syntax and semantics. Oversimplifying somewhat, a full lexical description involves a set of essentially disjoint hierarchies corresponding to these different aspects of linguistic description. These hierarchies are connected at the lexical entry nodes.
Exercise 6005
Complete the inheritance hierarchy for English verbs indicating informally the classes you take to be necessary and what their defining characteristics are.
Exercise 6006
Do the same for German verbs.
