Eckhard Bick - VISL

While inflexional ambiguity (2) concerns differences in word form categories,
lexical ambiguity can be subclassified according to whether it involves base forms
(1a), category inventory (i.e. morphological word class as I define it, 1b) or
differences in lexeme category (1c).
Representing the lowest level of context dependent rule based
disambiguation, morphological ambiguity (PoS, inflexion) needs special attention,
since rules can here only draw upon lexical/morphological context and on each
other, not on implicit information from any earlier levels of disambiguation. One by
one rules will then improve the quality ("unambiguity") of the context clues and thus
make life easier for each other.
Many morphological ambiguities can be resolved by using local context and
immediate group neighbourhood only (i.e. without global, unbounded rules). Thus
rules based on agreement are more prominent on this level than valency based
rules 70 . The more fundamental the ambiguity, the more profound a given reading's
impact on its surroundings will be, which is why PoS-ambiguity (1b, 3) is more
"important" for later stages of analysis than purely paradigmatic (1c) or inflexional
(2) ambiguity. In my Portuguese test text data, each PoS-error will on average cause
1-2 syntactic errors around it. Consequently, it is more permissible to use
portmanteau-tags for inflexion than for PoS, this being my choice in a few cases of
type (2) ambiguity, where many members of a word class lack a certain categorical
distinction, like gender in '-ar' -adjectives (M/F) and the present and perfeito simples
tense distinction in the 1.person plural of regular verbs (PR/PS). An especially
recalcitrant problem is (1a): In the example, all PoS and inflexion tags are the same,
but a difference in base form forces the parser to make a semantic lexeme distinction
that would otherwise belong to a much higher level of analysis (cp. chapter 3.7.2.1).
For the 'ir' - 'ser' pair, 35 rules are needed, many using higher level information, like
the copula-valency of 'ser' or the membership of 'ir' in the MOVE-class of
intransitive verbs.
Some traditional word class distinctions do not really belong on the
morphological level, but are rather syntactic classes derivable not from the words
morphological category inventory, but its syntactic uses:
(1) -ista noun or adjective ?
(2) "que" conjunction or pronoun or determiner ?
(3) "o" article or demonstrative pronoun ?
70 Though valency based rules may become necessary where everything else (short of semantics proper) proves
inapplicable, as in (1a).
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