Eckhard Bick - VISL

quite distinct, and few irregular exceptions exist. So most cases have to be lexical
homonyms. A relatively common case are words in '-r' or 'l' which can cover 2 different
lexemes, one masculine, one feminine (5a). Another possibility is lexicalised
metaphorical use (5b).
(5a)
(5b)
final
"final" ADJ M/F S 'last'
"final" N F S 'finale'
"final" N M S 'end'
cara
"cara" N F S 'face'
"cara" N M S 'guy'
"caro" ADJ F S 'expensive'
A certain amount of ambiguity is even purely syntactic or semantic, like much of the
ADV internal ambiguity where I have chosen to treat the relative () and
interrogative () subclasses of words like como, onde and quando as distinct
word classes, in order to achieve early disambiguation 78 (i.e., in this case, make
syntactic class information available at the PoS tagging level). Another example is the
topological - name ambiguity in Salvador, which can both be a place name (not
allowing an article) and a personal name (allowing the definite article).
Only such word class internal semantic ambiguity has a chance to survive the
tagger's disambiguation rule set, as the figures for the same VEJA text (6) show after
complete analysis (i.e. including disambiguation) 79 .
(6) Table: PoS-ambiguity resolved
N ADJ VFIN INF GER PCP ADV PROP all
pairs
- 122 -
precision
80
(%)
78 This is, of course, an exception, since secondary tags do not usually justify separate reading lines, and are not meant to be
disambiguated at the morphological stage. However, the above distinction in complementizer adverbials is of great
importance for the disambiguation of other - morphological - ambiguities, like the above mentioned FUT SUBJ vs. INF
readings, as well as for syntactic mapping (FS versus ICL).
79 Since the PoS error rate for automatic disambiguation is under 1% classes (cf. chapter 3.9.2) and fairly balanced between
word classes, there is nothing wrong with using the tagger's output after disambiguation as a base line for measuring
"disambiguation gain" in comparison with the ambiguity found before disambiguation.
80 Here defined as the ratio of word forms and word form readings, not , as in Karlsson et. al. (1995), correct readings
divided by all readings. The reason for my usage of the term is, that at nearly 100% disambiguation, the alternative
definition of 'precision' doesn't make much sense, since it will be close to the recall figure, both of which I therefore combine
as correctness (treated in 3.9). Recall without disambiguation (where it does make sense as an independent figure) is treated
in 2.2.6).