Eckhard Bick - VISL

compiled into a computer program that takes as input morphologically processed, but
still fully ambiguous text, as provided by lexicon and inflexion rule based analysers like
the one used in my own system, or the TWOL analysers (in the Helsinki systems, cp.
Koskenniemi, 1983). The multiple ambiguity represented by alternative tag lines, will
optimally be reduced to only one line 99 (the correct reading) by the CG-rule system.
(1) Constraint grammar input (morphological analyser output)
""
"nunca" ADV
""
"como" ADV
"como" ADV
"como" KS
"como" V PR 1S VFIN
""
"peixe" N M S
""
[ADV=adverb, KS=subordinating conjunction, V=verb, N=noun, PR=present tense, S=singular, M=maskuline, 1=1.person,
VFIN=finite verb, =relative, =interrogative, =monotransitive]
The four readings 100 of the word form 'como' are - in CG terminology - called a cohort.
A typical CG-rule 101 for disambiguating this ambiguity might be the following:
(2) SELECT (VFIN) IF (NOT *-1 VFIN) (NOT *1 VFIN)
[select for a given word form the VFIN reading (finite verb) if there is no (NOT) - neither to the left (*-1)
nor the right (*1) - other word that can be VFIN.] 102
By first adding ("mapping") all 103 possible syntactic functions onto a word form,
conditioned by its word class, inflexion etc., and then disambiguating this syntactic
99 Of course, in the case of true ambiguity (which is surprisingly rare in the world of corpus linguistics), two (or more)
correct tag lines are possible and should then be preserved.
100 The difference ADV and ADV is not really motivated by morphological word class, but expresses a
semantic-functional distinction (the English translation is 'like' in the first case, and 'as' in the second). It is of great
importance to polysemy resolution to determine which of a word's potential valency patterns has been instantiated in a given
clause context, and which semantic class fills a given valency slot. Here valency tags (and selection restrictions) gain
importance not only as secondary tags (that exclusively are used for the disambiguation of morphological/syntactic tags), but
also as primary tags in their own right, which can and must be ambiguated, like for the word form 'revista' , where simple
word class ambiguity (V-N) is turned into fourfold lexeme ambiguity:
rever V 'see again' instantiated valency: transitive
rever V 'leak through' instantiated valency: intransitive
revista N 'news magazine' instantiated valency: title , semantic class: reading matter
revista N 'inspection' instantiated semantic class: +CONTROL, +PERFECTIVE
101 The notation convention used here is the one used by Pasi Tapanainen's cg2-compiler, which among other things replaces
the older operators '@w=0' and '@w=!' with the ordinary English words 'REMOVE' med ' SELECT'.
102 The rule has been simplified, presuming that every sentence contains at least one finite verb, which isn't always the case,
in head lines, exclamations etc. The rule can be made safer by conditioning it on the existence of a full stop (*1
PUNKTUM) or by exploiting the possible valency relation between the transitive verb comer and the 'safe' peixe (0 )
(1C NP).
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