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Abstract

Commonsense knowledge about everyday concepts is an important asset for AI
applications, such as question answering and chatbots. Recently, we have seen
an increasing interest in the construction of structured commonsense knowledge
bases (CSKBs). An important part of human commonsense is about properties that
do not apply to concepts, yet existing CSKBs only store positive statements.
Moreover, since CSKBs operate under the open-world assumption, absent
statements are considered to have unknown truth rather than being invalid. This
paper presents the UNCOMMONSENSE framework for materializing informative
negative commonsense statements. Given a target concept, comparable concepts
are identified in the CSKB, for which a local closed-world assumption is
postulated. This way, positive statements about comparable concepts that are
absent for the target concept become seeds for negative statement candidates.
The large set of candidates is then scrutinized, pruned and ranked by
informativeness. Intrinsic and extrinsic evaluations show that our method
significantly outperforms the state-of-the-art. A large dataset of informative
negations is released as a resource for future research.