The DDTG implemented a set of rules that was meant to include much of the information gathered from the above sources. In implementing rhetorical relations, [Larson, 1984] and [Vander Linden et al., 1992] were the main sources. [Hovy, 1988] contributed much towards the implementation of formality.
Rhetorical Structures.
The main focus of the DDTG rule set was on implementing the causal rhetorical relations of reason-RESULT, means-RESULT and purpose- MEANS. The rules for these relations will be described, along with the simpler realizations of the other rhetorical relations present in the example text.
reason-RESULT
I. One sentence
A. reason is a state, easily made into an adjective, then use
reason-agent ``is'' ``so'' reason-adjective RESULT
``He was so angry he hit him''
B. reason in focus, then use
Result ``because'' reason
``We are not ruled by darkness because God rescued us''
C. else use
reason ``so that'' Result
``God rescued us so that we are not ruled by darkness''
II. Two sentences
A. use
reason. ``Because of this,'' Result.
``God rescued us. Because of this we are not ruled by darkness''
means-RESULT
I. agent(RESULT) = agent(means), then use
RESULT ``by'' means (progressive, omit agent)
``Jesus made peace by dying on the cross''
II. means able to be nominalized, use
RESULT ``by'' means (nominalized)
``God made peace by Jesus' death''
III. else use
RESULT ``because'' means
``God made peace because Jesus died on the cross''
purpose-MEANS
ordering:
means before purpose unless:
a) more than one means
b) purpose focused
form of purpose:
I. no sentence boundary between purpose and means
a. if infinitive possible, agent(purpose) = agent(MEANS), then use
``to'' purpose(infinitive, omit agent)
``He rose from the dead to be preeminent.''
b. nominalization possible, then use
``for'' purpose(nominalized)
``for desk installation''
c. if purpose agent is used in means also, progressive form
available, then use
``for'' purpose(progressive)
``for changing batteries''
d. else use
``in order that'' purpose (subjunctive mood with modal)
``in order that he might be preeminent''
II. Sentence boundary between purpose and means
a. if means is an action, then use
MEANS. pro(agent means) ``did this so that'' purpose(subjun)
``Jesus rose from the dead. He did this so that he would be
preeminent''
b. else use,
MEANS. ``The purpose of this is that'' purpose (subjunctive)
``Jesus rose from the dead. The purpose of this was that he
might be preeminent.''
Illustration
Head ``just like'' support
Equivalence
Head, ``that is'' support
Generic-specific
if agent(Generic) = agent(specific) then use
Generic, specific(progressive, omit agent)
``He redeemed us, forgiving us our sins''
else use
Generic. specific.
``He redeemed us. He forgave us our sins''
Formality.
Formality impacted on the text in several ways. The easiest to implement was the removal of complex verb forms such as nominalizations, perfects and subjunctives from the lexicon for informal texts. The second impact was on the ordering. For example, the means in a means-RESULT relation was fronted for more formal texts:
The final influence the formality level had on the realization of relations was in the choice of textual connectors. Compare the following informal markers with their corresponding formal markers below:
Of course, formality influenced the process of lexical choice as well. For instance, ``redeemed'' might be used in a more formal setting, whereas ``saved'' would be preferred in an informal one.