Hyper-relation

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Revision as of 19:24, 19 August 2013

Hyper-relation is a relation between relations, or between relations and nodes.

Basic symbols used in the UNL framework
Symbol	Definition	Example
( )	node	(%a)
" "	string	"went"
[ ]	natural language entry (headword)	[go]
[[ ]]	UW	[[to go(icl>to move)]]
//	regular expression	/a{2,3}/ = aa,aaa
rel(x;y)	relation	agt(kill;Peter)
^	not	^a = not a
{ \| }	or	{a\|b} = a or b
%	index for nodes, attributes and values	%x
:	scope ID	:01
#	index for sub-NLWs	#01
=	attribute-value assignment	POS=NOU
!	rule trigger	!PLR
&	merge operator	%x&%y
?	dictionary lookup operator	?[a]

Node: A node is the most elementary unit in the graph. It is the result of the tokenization process, and corresponds to the notion of "lexical item". At the surface level, a natural language sentence is considered a list of nodes, and a UNL graph a set of relations between nodes.
Relation: In order to form a natural language sentence or a UNL graph, nodes are inter-related by relations. In the UNL framework, there are three different types of relations: the linear (list) relation, syntactic relations and semantic relations.
Hyper-Node: A hyper-node is a sub-graph, i.e., a scope: a node containing relations between nodes.
Hyper-Relation: A hyper-relation is a relation between relations.

Hyper-relations and relations are represented in the same way, i.e.,

rel:scope(arg1;arg2;...;argn)

where:

The only difference between relations and hyper-relations is that the latter has at least one relation as one of its arguments, e.g.:

As in case of relations, the main scope is 00 and it is not shown, by default:

rel(rel1:01(arg1;arg2);arg3;...;argn) is the same as rel:00(rel1:01(arg1;arg2);arg3;...;argn) (i.e., the relation rel belongs to the main scope, i.e., the main graph)

Examples of hyper-relations

XP(XB(%a;%b);%c) - a syntactic relation XP between the syntactic relation XB(%a;%b) and the node %c
and(agt([a];[b]);agt([a];[c])) - a semantic relation "and" between the semantic relations agt([a];[b]) AND agt([a];[c])

XP(XB(%a;%b);%c) - the source argument of the hyper-relation XP is a relation
XP(%a;XB(%b;%c)) - the target argument of the hyper-relation XP is a relation
XP(VC(%a;%b);VA(%a;%c)) - the source and the target argument of the hyper-relation XP are relations
~~XP(VC(%a;%b)VA(%a;%c);VS(%a;%d))~~ - a hyper-relation may not have more than one relation as one single argument (in this case, the hyper-relation XP contained two relations as the source argument)

Differently from nodes, relations do not have elements (strings, headwords, features and elements)

~~XP(XB(%a;%b),"ab",[ab],[[ab]],A,B;%c)~~ (the relation XB(%a;%b) may not have strings, UWs, headwords or any features)

@@ Line 17: / Line 17: @@
 *rel(rel1(arg1;arg2);arg3;...;argn)
 As in case of [[relation]]s, the main scope is 00 and it is not shown, by default:
-*''rel(rel1:01(arg1;arg2);arg3;...;argn) '' is the same as rel:00(rel1:01(arg1;arg2);arg3;...;argn)  (i.e., the relation ''rel'' belongs to the main scope, i.e., the main graph)
+*''rel(rel1:01(arg1;arg2);arg3;...;argn) '' is the same as ''rel:00(rel1:01(arg1;arg2);arg3;...;argn)''  (i.e., the relation ''rel'' belongs to the main scope, i.e., the main graph)
 == Examples ==