“Knowledge extraction” isn't a real NLP term, I just came up with it to classify these methods that extract some kind of knowledge from text: definitions, axiomatic knowledge, etc.

• SemEval-2020 Task 6: Definition extraction from free text with the DEFT corpus Official task on codalab

• Sachan et al 2017 - From Textbooks to Knowledge: A Case Study in Harvesting Axiomatic Knowledge from Textbooks to Solve Geometry Problems