T-rule

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T-rules, or transformation rules, are rules that alter the state of the nodes. They are used for normalization, for syntactic analysis and for semantic interpretation. The set of the t-rules form the Transformation grammar, or T-Grammar.

Contents

Syntax

As describe in the UNL Grammar Specs, T-rules follow the general formalism:

<INITIAL STATE>:=<FINAL STATE>;

And may be classified according to the type of modification that they promote:

  • LL, or list-to-list, where the initial state and the final state are list structures
  • TT, or tree-to-tree, where the initial state and the final state are tree structures
  • NN, or network-to-network, where the initial state and the final state are network structures
  • LT, or list-to-tree, converts lists into trees
  • TL, or tree-to-list, converts trees into lists
  • TN, or tree-to-networks, converts trees into networks
  • NT, or network-to-trees, converts networks into trees

Types

According to their syntax and behavior, T-rules may be divided in:

  • LL (list-to-list) rules: alter a list structure
  • TT (tree-to-tree) rules: alter a tree structure
  • NN (network-to-network) rules: alter a network structure
  • LT (list-to-tree) rules: convert a list structure into a tree structure
  • TL (tree-to-list) rules: convert a tree structure into a linear structure
  • TN (tree-to-network) rules: convert a tree structure into a network structure
  • NT (network-to-tree) rules: convert a network structure into a tree structure

Examples

LL rules
  • (BLK):=; deletes a node that has the feature BLK
  • (A):=(+B); add the feature B to a node having the feature A
  • (A):=(-A); remove the feature A from a node having the feature A
  • (A):=(B)(C); replaces a node having the feature A by two nodes having the features B and C, respectively
  • (A)(B):=(C); replaces two nodes having the features A and B, respectively, by a node having the feature C
TT rules
  • XB(A;B):=; deletes the relation XB between two nodes having the features A e B, respectively]
  • XB(A;B):=XA(C;D); replaces the relation XB between two nodes having the features A and B, respectively, by a a relation XA between two nodes having the features C and D
  • XB(A;B):=XB(+C;-B); adds the feature C to the source argument and removes the feature B from the target argument of a relation XB where the the source node has the feature A and the target node has the feature B
  • XB(A;B):=+XC(C;D); adds the relation XC between two nodes having the features C and D, respectively, to the graph where exists a relation XB between two nodes having the feature A and B, respectively
NN rules
  • agt(A;B):=; deletes the relation agt between two nodes having the features A e B, respectively]
  • agt(A;B):=obj(C;D); replaces the relation agt between two nodes having the features A and B, respectively, by a a relation obj between two nodes having the features C and D
  • agt(A;B):=agt(+C;-B); adds the feature C to the source argument and removes the feature B from the target argument of a relation agt where the the source node has the feature A and the target node has the feature B
LT rules
  • (A)(B):=XB(C;D); replaces two nodes having the features A and B respectively by a relation XB between two nodes having the features C and D, respectively
TL rules
  • XB(C;D):=(A)(B); replaces the relation XB between two nodes having the features C and D, respectively, by two nodes having the features A and B, respectively
TN rules
  • XB(%a;%b):=agt(%a;%b); replaces the relation XB between two nodes %a and %b by a relation agt between the same nodes
NT rules
  • agt(%a;%b):=XB(%a;%b); replaces the relation agt between two nodes %a and %b by a relation XB between the same nodes

Special types of T-rules

According to their behavior, T-rules may also be classified in:

  • A-rules (affixation rules) apply over isolated word forms (as to generate possible inflections);
  • L-rules (linear rules) apply over lists of word forms (as to provide transformations in the surface structure);
  • S-rules (syntactic rules) apply over trees (as to modify the syntactic configuration).

Further information

For further information on t-rules, see the UNL Grammar Specs

Software