The definition of ā€˜understandā€™ by mathematicians is quite different from how we use the word in everyday conversation.

If you ā€œunderstandā€ a concept, you need to be able to answer the question of why the concept is correct. ā€œIt is written in the bookā€ is not a proper answer. You need to explain it in your own words. If the book uses a theorem or definition that you do not know, you must investigate it.

Yasuyuki Kawahigashi prohibits to see notes at the seminar. He defines ā€œunderstandā€ as the state which you can explain the concept with your own words without seeing anything. en.icon

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