Designing an Anaphora Resolution Algorithm for Route Instructions
Designing an Anaphora Resolution Algorithm for Route Instructions
Designing an Anaphora Resolution Algorithm for Route Instructions
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Even though the first Final Sentence Rule defined like this will not correctly resolve<br />
all <strong>an</strong>aphors occurring in final sentences, it expresses the preference that <strong>an</strong>aphors<br />
marked as I-incompatible more often refer to the task (which refers to the sequence of<br />
events taking the robot to the destination) th<strong>an</strong> to a single event of the route<br />
instruction. This rule describes <strong>an</strong>other domain specific phenomenon.<br />
The second Final sentence rule deals with <strong>an</strong>aphoric reference to the<br />
destination without explicitly mentioning the destination in the utter<strong>an</strong>ces preceding<br />
the <strong>an</strong>aphor. This phenomenon occurs quite often in data. For resolving the <strong>an</strong>aphor<br />
mentioned in the final sentence to the destination stored in the discourse model, the<br />
algorithm firstly has to check whether the <strong>an</strong>aphor is a pronoun, as this was the case<br />
in all the examples found in the data; replacing the pronoun by a demonstrative<br />
sounds odd (cf. examples 8 <strong>an</strong>d 9).<br />
8) <strong>an</strong>d it is on your left there<br />
9) <strong>an</strong>d that is on your left there<br />
Secondly, the properties of the <strong>an</strong>aphor have to match the properties of the<br />
destination (usually only the type constraint: ‘building’). Finally, the algorithm has to<br />
find out if the destination is mentioned in one of the previous utter<strong>an</strong>ces (e.g. if<br />
unit(4) is the final unit, units(3 <strong>an</strong>d 2) have to be checked). If all these conditions are<br />
fulfilled, the <strong>an</strong>aphor is resolved to the destination stored in the discourse model. If<br />
the <strong>an</strong>aphor does not match the properties of the destination, the Pronominal<br />
<strong>Anaphora</strong> Rules (see below) are applied. If the destination is mentioned in one of the<br />
previous units, the <strong>an</strong>aphor is resolved to the most recently mentioned destination.<br />
Be<strong>for</strong>e the next rules are explained, it needs to be said that it is assumed <strong>for</strong> the First<br />
<strong>an</strong>d Final sentence rules that the algorithm is able to recognise the first <strong>an</strong>d final<br />
sentence of the route instructions.<br />
The remaining <strong>an</strong>aphors, either pronominal <strong>an</strong>aphors (‘it’, ‘this’ <strong>an</strong>d ‘that’), or<br />
‘This-NP’-<strong>an</strong>aphors (e.g. ‘that road’) are resolved by the Pronominal <strong>Anaphora</strong><br />
Rules <strong>an</strong>d This-NP-<strong>Anaphora</strong> Rules respectively. The Pronominal <strong>Anaphora</strong> Rules<br />
use the concept of the S-List or of the A-List is in order to determine the <strong>an</strong>tecedent<br />
of the <strong>an</strong>aphor while the ‘This-NP’-<strong>an</strong>aphora rules additionally employ the implicit<br />
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