Hyper-node

Hyper-nodes are nodes containing relations between nodes. They represent scopes or sub-graphs.

Basic Symbols

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]

Basic Concepts

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.

Notation

As any node, hyper-nodes are represented between (parentheses):

• (("a")("b")) - a hyper-node containing a list relation between two nodes
• (L("a";"b")) - the same as above
• (VC("a";"b")) - a hyper-node containing a syntactic relation VC between two nodes
• (agt("a";"b")) - a hyper-node containing a semantic relation agt between two nodes

For better readability, hyper-nodes may also be referenced by :XX, where XX is a unique identifier for the hyper-node:

• and((L("a";"b"));"c") - a relation "and" between the hyper-node (L("a";"b")) and the node "c"

is the same as

• and(:01;"c")
• L:01("a";"b")

Elements

As any node, hyper-nodes are vectors (uni-dimensional) arrays containing the following necessary elements:

• a string, represented between "quotes"
• a headword, represented between [simple square brackets]
• a UW, represented between [[double square brackets]]
• features, of which the internal relations are a special type
• an index, preceded by %

Examples

Examples of hyper-nodes are the following:

• (("a")("b")) - a hyper-node containing a linear relation between the nodes ("a") and ("b")
• (VC(%x;%y)VA(%x;%z)) - a hyper-node containing two syntactic relations: VC(%x;%y) AND VA(%x;%z)
• (agt([a];[b])obj([a];[c])) - a hyper-node containing two semantic relations: agt([a];[b]) AND obj([a];[c])
• (([kick],V)([the],D)([bucket],N),V,NTST) - a hyper-node having the features N and NTST and containing two linear relations: one between the nodes ([kick],V) and ([the],D), and other between ([the],D) and [bucket],N)
• (([kick],V)([the],D)([bucket],N),"kick the bucket",[[die]],V,NTST) - the same as before, except for the fact that the hyper-node has string = "kick the bucket" and UW = [[die]]

Hyper-nodes may also contain internal hyper-nodes:

• ((("a")("b"))("c")) - a hyper-node containing a linear relation between the hyper-node (("a")("b")) and the node ("c")

Properties of hyper-nodes

As any node, hyper-nodes are expressed between (parentheses)

(("a")("b"))

As any node, hyper-nodes may have one single string, one single headword and one single UW, but may have as many features and internal relations as necessary

(([kick],V)([the],D)([bucket],N),"kick the bucket",[kick the bucket],[[die]],V,NTST)

As any node, hyper-nodes may be referenced by any of its elements, including internal relations

(([kick],V)) - refers to any hyper-node containing the node ([kick],V)

(([the],D)([bucket],N)) - refers to any hyper-node containing a linear relation between ([the],D) AND ([bucket],N)

(([kick],D),([bucket],N)) - refers to any hyper-node containing the nodes ([kick],V) AND ([bucket],N)

When a hyper-node is deleted, all its internal relations are deleted as well

(([kick],V)([the],D)([bucket],N)):=; (the hyper-node is deleted, as well as the relations ([kick],V)([the],D) AND ([the],D)([bucket],N))