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Research on Logic and Computation in Hypothesis Finding
Research on Logic and Computation in Hypothesis Finding
山本, 泰生
ヤマモト, ヨシタカ
YAMAMOTO, Yoshitaka
総合研究大学院大学
博士（情報学）
The thesis studies the logical mechanism and its computational proce-
dures in hypothesis finding. Given a background theory and an observation
that is not logically derived by the prior theory, we try to find a hypothesis
that explains the observation with respect to the background theory. The
hypothesis may contradict with a newly observed fact. That is why the logic
in hypothesis finding is often regarded as ampliative inference.
In first-order logic, the principle of inverse entailment (IE) has been ac-
tively used to find hypotheses. Previously, many IE-based hypothesis finding
systems have been proposed, and several of them are now being applied to
practical problems in life sciences concerned with the study of living or-
ganisms, like biology. However, these state-of-the-art systems have some
fundamental limitation on hypothesis finding: They make the search space
restricted due to computational efficiency. For the sake of incompleteness in
hypothesis finding, there is an inherent possibility that they may fail to find
such sufficient hypotheses that are worth examining.
The thesis first provides such a practical problem, where those incomplete
procedures cannot work well. In contrast, this motivating problem is solved
by CF-induction, which is an IE-based procedure that enables us to find
every hypothesis. On the other hand, complete procedures like CF-induction
have to deal with a huge search space, and thus, are usually achieved by
consisting of many non-deterministic procedures.
The thesis next shows an alternative approach for finding hypotheses,
which is based on the inverse relation of subsumption, instead of entailment.
The proposed approach is used to simplify the IE-based procedures by reduc-
ing their non-determinisms without losing completeness in hypothesis finding.
Together with this result, we logically reconstruct the current procedure of
CF-induction into a more simplified one, while it ensures the completeness.
Through the thesis, we will see underlying nature and insights to overcome
limitations in the current lE-based hypothesis finding procedures.
application/pdf
総研大甲第1385号
thesis
2010-09-30
application/pdf
application/pdf
https://ir.soken.ac.jp/record/2171/files/甲1385_要旨.pdf
https://ir.soken.ac.jp/record/2171/files/甲1385_本文.pdf
eng