Universal Attributes

Revision as of 20:07, 14 December 2010

Attributes are arcs linking a node to itself. In opposition to relations, they correspond to one-place predicates, i.e., functions that take a single argument. In UNL, attributes have been normally used to represent information conveyed by natural language grammatical categories (such as tense, mood, aspect, number, etc). The set of attributes, which is claimed to be universal, is defined in the UNL Specs and is not open to frequent additions.

Syntax

The syntax of attributes is defined as follows:

<attribute>      ::= "@"<attribute name>
<attribute name> ::= <character>+
<character>      ::= {“a”,...,“z”,“_”}

where:
< > variable
" " terminal symbol
::=... is defined as ...
{ } disjunction ("or")
+ to be used one or more times
... to be repeated more than 0 times

Attribute names are always lower case words or expressions. Normally, English words ("past", "will") or mnemonic abbreviations ("def", "pl") are used for attribute labelling. No blank space is allowed inside an attribute name.

Semantics

Attributes are annotations made to nodes or hypernodes of a UNL hypergraph. They denote the circumstances under which these nodes (or hypernodes) are used.

Attributes may convey three different kinds of information:

• The information on the role of the node in the UNL graph (as in the case for '@entry', that indicates the main (starting) node of a UNL directed graph);
• The information conveyed by bound morphemes and closed classes, such as affixes (gender, number, tense, aspect, mood, voice, etc), determiners (articles and demonstratives), adpositions (prepositions, postpositions and circumpositions), conjunctions, auxiliary and quasi-auxiliary verbs (auxiliaries, modals, coverbs, preverbs) and degree adverbs (specifiers).
• The information on the (external) context of the utterance, i.e., non-verbal elements of communication, such as prosody, sentence and text structure, politeness, schemes, social deixis and speech acts.

Set of attributes

List of attributes in alphabetical order