Transformation over relations
(→Altering nodes in a relation) |
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Nodes are deleted when they are not co-indexed to any node in the right side (see [[Indexation]]): | Nodes are deleted when they are not co-indexed to any node in the right side (see [[Indexation]]): | ||
*rel(%x,A;%y,B;'''%z,C'''):=rel(%x;%y); (the node %z is deleted as an argument of the relation rel) | *rel(%x,A;%y,B;'''%z,C'''):=rel(%x;%y); (the node %z is deleted as an argument of the relation rel) | ||
| − | Nodes are | + | Nodes are completelly deleted if, and only if, they are not part of any other relation |
=== Creating relations === | === Creating relations === | ||
Relations are created by the operator + (add) before the relation to be created. This operator may not be omitted. | Relations are created by the operator + (add) before the relation to be created. This operator may not be omitted. | ||
*rel(%x;%y):=+rel2(%x;%z); (a new relation rel2 is created between the nodes %x and %z; the original relation is not altered) | *rel(%x;%y):=+rel2(%x;%z); (a new relation rel2 is created between the nodes %x and %z; the original relation is not altered) | ||
| − | Creation of relations is a possible source of infinite loops. In order to prevent the rule from applying eternally, the | + | Creation of relations is a possible source of infinite loops. In order to prevent the rule from applying eternally, the condition field must be controlled: |
| − | *rel(%x;%y)^rel2(%x;%z):=+rel2(%x;%z); | + | *rel(%x;%y)^rel2(%x;%z):=+rel2(%x;%z); |
=== Deleting relations === | === Deleting relations === | ||
Latest revision as of 12:51, 5 November 2013
Relations are altered, replaced, created and deleted by S-rules:
Contents |
Altering nodes in a relation
Elements of nodes in relations are altered through the operators + (add) and - (delete). The operator + may be omitted.
- rel(%x,A;%y,B):=rel(%x,+C;%y,+D); (add the feature C to %x and D to %y)
- rel(%x,A;%y,B):=rel(%x,C;%y,D);(the same as above)
- rel(%x,A;%y,B):=rel(%x,-A;%y); (delete the feature A from %x)
"strings", [headwords] and [[UWs]] are considered to be features (but a single node may have only one of each)
- rel(%x;%y):=rel(%x,"a";%y); (replace the existing string in %x, if any, by "a")
- rel(%x;%y):=rel(%x,[A];%y);(replace the existing headword in %x, if any, by [A])
- rel(%x;%y):=rel(%x,[[A]];%y); (replace the existing UW in %x, if any, by [[A]])
Creating nodes in a relation
Nodes are created when they are not co-indexed to any node in the left side (see Indexation):
- rel(%x,A;%y,B):=rel(%x;%y;%z,+A); (the node %z, with the feature A, is created as a new argument of the relation rel)
Deleting nodes in a relation
Nodes are deleted when they are not co-indexed to any node in the right side (see Indexation):
- rel(%x,A;%y,B;%z,C):=rel(%x;%y); (the node %z is deleted as an argument of the relation rel)
Nodes are completelly deleted if, and only if, they are not part of any other relation
Creating relations
Relations are created by the operator + (add) before the relation to be created. This operator may not be omitted.
- rel(%x;%y):=+rel2(%x;%z); (a new relation rel2 is created between the nodes %x and %z; the original relation is not altered)
Creation of relations is a possible source of infinite loops. In order to prevent the rule from applying eternally, the condition field must be controlled:
- rel(%x;%y)^rel2(%x;%z):=+rel2(%x;%z);
Deleting relations
Relations are deleted when they are not repeated in the right side, except in case of +
- rel(%x;%y):=; (the relation rel between the nodes %x and %y is deleted)
- rel(%x;%y):=rel2(%x;%y); (the relation rel between %x and %y is deleted and a new relation rel2 is created in its place) (replacement)
- rel(%x;%y):=+rel2(%x;%y); (the relation rel is preserved and a new relation rel2 is created) (creation)
Replacing relations
Relations in the left side are replaced by relations in the right side, except in case of +:
- rel(%x;%y):=rel2(%x;%y); (the relation rel between %x and %y is deleted and a new relation rel2 is created in its place)
- rel1(%x;%y)rel2(%y;%z):=rel3(%x;%z); (the relations rel1 and rel2 are deleted and a new relation rel3 is created in their place) (merge)
- rel(%x;%y):=rel1(%x;%y)rel2(%y;%z); (the relation rel is deleted and two new relations rel1 and rel2 are created in its place) (divide)
- (%x)(%y):=rel(%x;%y); (the linear relation between the nodes %x and %y is replaced by the non-linear relation rel between the same nodes)
- L(%x;%y):=rel(%x;%y); (the same as above)
