Universal Networking Language (UNL) is an Interlingua developed by UNDL foundation. UNL is in the form of semantic network to represent and exchange information. Concepts and relations enable encapsulation of the meaning of sentences. In UNL, a sentence can be considered as a hypergraph where each node is the concept and the links or arcs represent the relations between the concepts. UNL knowledge base provides concepts for the words in the natural language sentences.
The UNL consists of Universal Words (UWs), Relations and Attributes and knowledge base.
Universal Words (UWs)
Universal words are UNL words that carry knowledge or concepts. UWs are simply nodes in the UNL graph. There are two type of UWs: permanent and temporary. Permanent UWs represent concepts of common use and are included in the UW dictionary. Temporary UWs may represent new concepts, too specific or not translatable so that they are not included in the dictionary.
Examples:
bucket(icl>container)
water(icl>liquid)
Relations
Relations are labelled arcs that connect nodes (Uws) in the UNL graph. The relations are binary and usually represent semantic cases and semantic roles.
Examples:
agt ( break(agt>thing,obj>thing), John(iof>person) )
Attributes
Attributes are annotations used to represent grammatical categories, mood, aspect, etc. Every attribute starts with “@” symbol.
Example:
work(agt>human).@past
– means that the tense of the verb work is past tense, that is , it is actually worked in the sentence.
Knowledge Base
The UNL Knowledge Base contains entries that define possible binary relations between UWs.