obl:arg: oblique argument
The relation obl:arg is used for oblique arguments and distinguishes them from
adjuncts, which use the plain obl relation. It is thus possible to preserve
the notion of object as it is defined in the Czech grammar and annotated in
the Prague family of treebanks.
Objects in Czech can be bare noun phrases in accusative, dative, genitive or
instrumental cases, and prepositional phrases in accusative, dative, genitive,
instrumental or locative. Most of these coding strategies are also used for
adjuncts (called adverbial modifiers in the Czech grammar).
However, Universal Dependencies reserve the relation obj (object) for the
core object, and exclude oblique arguments. In Czech UD, we treat bare nominals
(including non-accusatives) as core arguments and prepositional phrases as
obliques. Within obliques, the obl:arg subtype is used for oblique arguments
(i.e., prepositional objects), and the plain obl is used for adjuncts.
Spoléhám se na jeho instinkt . \n I-rely REFL on his instinct .
obl:arg(Spoléhám, instinkt)
obl:arg(I-rely, instinct)
case(instinkt, na)
case(instinct, on)
The relation obl:arg is a language-specific subtype (as opposed to universal type)
because the argument-adjunct distinction is not made at the universal level
(some discussion is here).
However, it is available in Czech treebanks and obl:arg ensures that it is
not lost. Users that require reliable comparison across languages can easily
reduce it to obl.
Arguments are selected by the predicate. Their coding (preposition and morphological case) is determined by the predicate; within the set of arguments of this predicate, the coding maps the argument to a particular semantic role. In contrast, the semantics of an adjunct is relatively independent of the predicate, and typical adjuncts (such as specifications of time, location, manner or instrument) can combine with a large number of different predicates.
Hence in the above example, the preposition na and the accusative case of the noun instinkt are selected by the verb spoléhat. Other verbs may also select the same preposition and case but the meaning will be different: for instance, myslet na někoho “to think of someone.” Finally, the preposition na itself has an adessive or allative meaning (see the corresponding values of the Case feature). This meaning is suppressed when the preposition is selected by a predicate but it is more recognizable in adjuncts. In the following example, the preposition combines with a noun phrase in the locative case and marks a locational modifier:
Konference se koná na Slovensku . \n Conference REFL takes-place in Slovakia .
obl(koná, Slovensku)
obl(takes-place, Slovakia)
case(Slovensku, na)
case(Slovakia, in)
obl:arg in other languages: [bej] [cs] [de] [fr] [pl] [qpm] [u] [xcl]