Document description

In this document we’ll illustrate some examples using DT patterns for relation extraction. The patterns we use in this document are meant to show the reader how to exclude dependency bindings (a dependency binding is a triple consisting of a syntactic dependency link [StanfordDependenciesManual—2008], the governor and the dependent) in a pattern in order to improve the accuracy of the pattern.

Remarks

We inform the reader that the dependency links and the part of speech tags used in the patterns and examples are produced by the Stanford Full Parser version 3.3.1 (which can be found at [StanfordFullParser]). However, the patterns can include any dependency links or POS tags of the chosen of the user.

For more details on the dependency links used in this document we refer the reader to [StanfordDependenciesManual—2008].

The figures related to sentence syntactic trees and visual representation of DT patterns, and also references are put at the end of this document.

Related Patterns

Pattern1

#<relationName>=<verb>_<preposition>#

#<domain>=<subject>#

#<range>=<prepositionalObject>#

nsubj(<verb>(VBZ|VBN|VBD),<subject>(NNP|NN|NNS));

pobj(<preposition>(IN|TO),<prepositionalObject>(NNP|NN|NNS));

prep(<verb>(VBZ|VBD|VBN),<preposition>(IN|TO));

Fig. 1. (dtp1) A DT pattern for extracting semantic relations from intransitive verb phrases

Pattern2

#<relationName>=<verb>_<directObject>_<preposition>#

#<domain>=<subject>#

#<range>=<prepositionalObject>#

nsubj(<verb>(VBZ|VBN|VBD),<subject>(NNP|NN|NNS));

pobj(<preposition>(IN|TO),<prepositionalObject>(NNP|NN|NNS));

prep(<verb>(VBZ|VBD|VBN),<preposition>(IN|TO));

dobj(<verb>(VBZ|VBN|VBD),<directObject>(NNP|NN|NNS));

Fig. 2. (dtp2) A DT pattern for extracting semantic relations from intransitive verb phrases

Pattern3

#<relationName>=<verb>_<preposition>#

#<domain>=<subject>#

#<range>=<prepositionalObject>#

nsubj(<verb>(VBZ|VBN|VBD),<subject>(NNP|NN|NNS));

pobj(<preposition>(IN|TO),<prepositionalObject>(NNP|NN|NNS));

prep(<verb>(VBZ|VBD|VBN),<preposition>(IN|TO));

!dobj(<verb>(VBZ|VBN|VBD),<directObject>(NNP|NN|NNS));

Fig. 3. (dtp3) A DT pattern for excluding a dependency binding in order to improve the accuracy of (dtp1)

Examples

The example 1 is meant to underline the need for excluding bindings in a DT pattern.

The exclusion of dependency bindings can be done by putting the character ‘!’ next to the dependency binding to exclude, it means that when the pattern match with a sub-tree of the syntactic tree of a sentence, then the excluded binding (linking the matched governor and the matched dependent) should not exist (in the matched sub-tree) when the match occurs.

For instance, in the DT pattern (dtp1) in Figure 1, to exclude the dependency binding dobj(<verb>(VBZ|VBN|VBD),<directObject>(NNP|NN|NNS)) then it suffices to add the ‘!’ character which results in !dobj(<verb>(VBZ|VBN|VBD),<directObject>(NNP|NN|NNS)) of (dtp3) in Figure 3.

Example1

Matching (dtp1) with the dependency tree (t1) in Figure 4 (the syntactic dependency tree of the sentence (s1) “The Ebola virus causes internal bleeding to its victims.”) allows to extract the relation cause_to(virus,victim) (r1), while matching (dtp2) (notice that (dtp1) is a sub-tree of (dtp2)) with (t1) allows to extract the relation cause_bleeding_to(virus,victim) (r2) which is more meaningful than (r1). Matching (dtp1) with the dependency tree (t2) in Figure 5 (the syntactic dependency tree of the sentence (s2) “Van Gogh lived in Paris.”) allows to extract the relation live_in(gogh,paris) (r3) which (in contrast with (r1)) is meaningful.

It is needed to make a pattern similar to (dtp1) that can match with (t2) but not with (t1). The pattern (dtp3) is intending to show how (dtp1) can be transformed to be more accurate.

Matching (dtp3) (notice the excluded binding dobj(<verb>(VBZ|VBN|VBD),<directObject>(NNP|NN|NNS))) with (t2) allows to extract (r3) but not (r1) when it (i.e. the pattern (dtp3)) is matched with (t1). This is due to the exclusion of the dependency binding dobj(<verb>(VBZ|VBN|VBD),<directObject>(NNP|NN|NNS)).

Figures

Fig. 1. (tdtp1) A visual representation of the DT pattern (dtp1)

Fig. 2. (tdtp2) A visual representation of the DT pattern (dtp2)

Fig. 3. (tdtp3) A visual representation of the DT pattern (dtp3)

Fig. 4. (t1) the syntactic dependency tree of the sentence (s1)

Fig. 5. (t2) the syntactic dependency tree of the sentence (s2)

References

[StanfordDependenciesManual—2008]

Marie-Catherine de Marneffe & Christopher D. Manning, 2008. Stanford typed dependencies manual: http://nlp.stanford.edu/software/dependencies_manual.pdf.

[StanfordFullParser]

http://nlp.stanford.edu/software/lex-parser.shtml