Eckhard Bick - VISL

words: 40.8 10.5 17.9 2.9 0.5 3.1 8.2 6.9 71.0
Table (2) shows the relative risks of a word class WC1 word form to be WC1-WC2
ambiguous. The percentage given is the ratio between the frequency of this ambiguity
class and the frequency of words with at least one WC1 reading: WC1&WC2/WC1. For
example, 15.7% of all words with N readings are ambiguous with at least one VFIN
reading. The isolated word class frequencies for the undisambiguated text are given in
the last row (shaded, e.g. for N, 40.8%).
My ambiguity index is not a percentage, but the sum of all instances of different
ambiguity pairs for a word class WC1 (given in the last column in table 1, i.e. for VFIN,
28.274, the sum of VFIN-N, VFIN-ADJ, VFIN-VFIN, VFIN-INF and so on), divided
by the number of all VFIN candidate word forms (30.619). The resulting figure looks
like a percentage, in fact, it is the sum of all percentages in one row, yet due to the fact
that many word forms host several WC ambiguity pairs, this "sum" is somewhat higher
than what would be the "real" percentage of ambiguous instances for that word class.
The overall ambiguity index for open word class ambiguity (45.1) is calculated as the
ratio between the sum of all WC ambiguity instances (equalling half the sum of the last
column in table 1, minus the shaded boxes), divided by the number of open word class
candidates.
Maybe the most striking result is the fact that nouns appear to be frequent but
harmless, while adjectives and participles are rarer, but very likely to belong too another
nominal 77 class, too. The reason for the latter is a semantico-etymological one - many
participles tend to be treated lexicographically as adjectives, and many adjectives
function as nouns, too. Since lexicography is often bilingually motivated, and word
classes often defined functionally, adjectives like dinamarquês ('Danish') are also listed
as nouns ('Dane'), though there is no morphological reason for this - even the lexeme
category test fails, since these nouns often - atypically - possess gender inflexion like
their adjective counterpart. In the case of ADJ-PCP ambiguity, the parser is set to
routinely discard the ADJ reading, and only "remember" it for later translational
purposes, by adding an tag. However, this is done after the tagging stage,
though the full ambiguity is preserved in table (2).
The most dangerous case, however, are VFIN readings. Because of finite verbs'
crucial role in syntactic mapping, the nearly 50% chance of VFIN-nominal ambiguity
(N, ADJ, PCP, PROP combined) is disconcerting, which is why I will provide a short
assessment of this particular disambiguation task ante temporem. Several
morphologically different endings cases can be distinguished:
(3)
77 ‘Nominal’ is here used as an umbrella term for the open word classes defined by number and gender (N, ADJ, PCP and,
where relevant, PROP)
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