Sentiment Analysis based on Appraisal Theory and Functional Local ...

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I introduce here the concept of an appraisal expression, a basic grammatical
structure expressing a single evaluation, <strong>based</strong> on linguistic analyses of evaluative
language [20, 21, 72, 110], to correctly capture the full complexity of opinion expressions.
In an appraisal expression, in addition to the evaluator (the person to whom
the opinion is attributed), attitude, and target, other parts may also be present, such
as a superordinate when the target is evaluated as a member of a class or an aspect
when the evaluation only applies in a specific context (see examples 5 thru 7).
(5) “
target
She’s the
attitude
most heartless
superordinate
coquette
aspect
in the world,”
evaluator
he cried, and clinched his hands.
(6)
evaluator
I
attitude
hate it
target
when people talk about me rather than to me.
(7)
evaluator
He opened with
expressor
greetings of gratitude and
attitude
peace.
I view extracting appraisal expressions as a fundamental subtask in sentiment
analysis, which needs to be studied on its own terms. Appraisal expression extraction
must be considered as an independent subtask in sentiment analysis because it can
be used by many higher level applications.
In this dissertation, I introduce the FLAG 1 appraisal expression extraction
system, and the IIT <strong>Sentiment</strong> Corpus, designed to evaluate performance at the task
of appraisal expression extraction.
1.3 Evaluating Structured Opinion Extraction
In addition to the problems posed by trying to cram a complicated opinion
structure into an annotation scheme that only recognizes attitudes and targets, much
of the work that’s been performed in structured opinion extraction has not been
1
FLAG is an acronym for “Functional Local Appraisal Grammar”, and the technologies
that motivate this name will be discussed shortly.