Content Differences in Syntactic and Semantic Representations

This page provides detailed examples to accompany the following paper:

@inproceedings{hershcovich2019content,
    title = "Content Differences in Syntactic and Semantic Representation",
    author = "Hershcovich, Daniel  and
      Abend, Omri  and
      Rappoport, Ari",
    booktitle = "Proc. of NAACL-HLT",
    url = "https://www.aclweb.org/anthology/N19-1047",
    pages = "478--488"
}

In addition, see the following for the full EWT Reviews data:

• Gold-standard UCCA visualization.
• Gold-standard UCCA sentences XMLs.
• Gold-standard UD.

For a broader perspective on meaning representations, take a look at the CoNLL 2020 shared task on Cross-Framework Meaning Representation Parsing.

Scene/Non-Scene

A major distinction in UCCA is between scene-evoking phrases and non-scene-evoking ones.

Participant nsubj

Noun subjects, and core syntactic arguments in general, are predominately UCCA Participants. in the following, wine is both nsubj and Participant, as it is not a scene-evoking noun, but participates in the excellent scene:

Process nsubj

In contrast, in the following, the noun subject service is scene-evoking, and corresponds to a UCCA Process:

Linker nsubj

Non-scene-evoking nouns can also correspond to UCCA Linkers, as in the following example, where the relative pronoun who is a noun subject but serves as a Linker between two Parallel Scenes.

Adverbial amod

Adjectives can be scene-evoking or not. Different classes of adjectives are handled differently in UCCA: e.g., while most adjectives are scene-evoking, pertainyms (academic), inherent-composition modifiers (sugary), and quantity modifiers (many) are not. Some adjectives are ambiguous: a legal practice may refer to a behavior that is legal as opposed to illegal, in which case it should be scene-evoking, or to a law office, in which case it should not. In the following, perfect evokes a scene and is annotated as a State, whereas romantic does not evoke a scene and is instead an Adverbial in the dinner scene.

State amod

Another example for a scene-evoking adjective follows, where the adjective beautiful is annotated as a State.

Similarly, convenient in the following sentence evokes a State:

Elaborator amod

The most common case of adjectives is as Elaborators of non-scene units. In the following, medical is al Elaborator of the non-scene school (whereas poor is an Adverbial in the rating scene).

Participant nmod

Noun modifiers can also have various different semantic roles. For example, on services, modifying discount in the following, is a Participant in the discount scene. Note that in this case, a discount is also a Participant in the scene evoked by the services Process.

Possessives, such as our in the following, our noun modifiers annotated as Participants in the possession scene (our decision), which is itself an Elaborator of the modified noun. This is another example of a complex annotation.

Elaborator nmod/acl

Noun modifiers of non-scenes, on the other hand, are Elaborators, such as my car’s in the following, modifying gears and brakes:

Similarly, the scene that work there, modifying the non-scene younger kids, is an Elaborator clausal modifier.

Unmatched acl

Some clausal modifiers do not match any UCCA units, such as I got in the following. This is an instance of a free relative clause, where what I got is a unit in UCCA but what is a separate obj in UD.

Relator case

Prepositions are mostly Relators, modifying non-scenes, such as at modifying Bradley Chevron in the following. On the other hand, the preposition for is a Linker between the Paralell Scenes corresponding to running and death.

Linker case

This is another example of a preposition serving as a Linker between two scenes: with links the Informative and work scenes.

Elaborator case

A very diverse class, prepositions can also serve as Elaborators, which is the case for comparators such as over in over a year:

State case

Prepositions can even evoke scenes, such as on in the following:

Connector cc

Coordinating conjunctions are typically connectors, when they connect non-scene-evoking units. This is the case for Mercedes and Dan in the following, but not for the other and, which is a Linker between the thorough and on top scenes:

Linker cc

Similarly, but is a coordinating conjunction Linker between two scenes in the following:

Elaborator det

While articles (a/the) are Functions, determines that are demonstratives serve as Elaborators:

Adverbial det

Determiners can also be Adverbials, for example when expressing negation:

Other determiners modifying scenes are also Adverbials, such as what in what a mistake:

This is also the case for some in the following, modifying the scene leakage:

Primary/Secondary Relations

Another major distinction in UCCA is between primary relations (Process/State), secondary relations (Adverbials) and Participants.

Adverbial advmod

Adverbs are typically Adverbials, although not necessarily so. In the following, sometimes is such as example:

Participant advmod

Adverbs can also be Participants if they designate a location:

Adverbial obl

On the other hand, oblique modifiers of predicates (introduced by prepositions) can also be Adverbials. They serve a similar role to adverbs, but are distinguished in UD due to the syntactic realization. For example by far in the following is an Adverbial functioning as an oblique modifier:

Participant csubj

Clausal subjects, similarly to noun subjects, are typically participants (they did not charge …):

Participant ccomp

Clausal complements, too, are core arguments and are typically Participants (what i wanted):

Participant xcomp

The same is true for open clausal complements (to change it):

Unmatched xcomp

However, many clauses (open clausal complements in particular) do not correspond to any UCCA unit, due to markers attaching to the clause in UD but annotated as Linkers between scenes in UCCA, or due to multiple scenes whose segmentation may be ambiguous, as in to pay for you to use them:

State xcomp

Function aux

Adverbial aux

Multi-Word Expressions

Elaborator compound

Unmatched compound

Participant compound

Adverbial compound

Unmatched obj

Unmatched advcl

Linkage

Head selection

Parallel Scene advcl

Parallel Scene parataxis

Linker wh-pronoun

Linker oblique

Other

Apposition

State copula (expressing identity)

Function copula (expressing attribution/location)

Ground discourse

Ground + Participant vocative

Function nsubj (expletive)

Site powered by Annodoc and brat