Tag Archives: 고성훈

Solution: 2019-21 Approximate isometry

Let \( A \) be an \( m \times n \) matrix and \( \delta \in (0, 1) \). Suppose that \( \| A^T A – I \| \leq \delta \). Prove that all singular values of \( A \) are contained in the interval \( (1-\delta, 1+\delta) \).

The best solution was submitted by 고성훈 (수리과학과 2018학번). Congratulations!

Here is his solution of problem 2019-21.

A similar solution was submitted by 김태균 (수리과학과 2016학번, +3). Incomplete solutions was submitted by 박재원 (2019학번, +2), 하석민 (수리과학과 2017학번, +2).

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Concluding 2018 Spring

Thanks all for participating POW actively. Here’s the list of winners:

1st prize (Gold): Lee, Jongwon (이종원, 수리과학과 2014학번)
2nd prize (Silver): Chae, Jiseok (채지석, 수리과학 과 2016학번)
2nd prize (Silver): Han, Joon Ho (한준호,수리과학과 2015학번)
2nd prize (Silver): Lee, Bonwoo (이본우, 수리과학과 2017학번)
3rd prize (Bronze): Ko, Sunghun (고성훈, 2018학번)

이종원 (수리과학과 2014학번) 40/40
채지석 (수리과학과 2016학번) 35/40
한준호 (수리과학과 2015학번) 35/40
이본우 (수리과학과 2017학번) 32/40
고성훈 (2018학번) 20/40
김태균 (수리과학과 2016학번) 19/40
최인혁 (물리학과 2015학번) 10/40
김건우 (수리과학과 2017학번) 8/40
최백규 (생명과학과 2016학번) 6/40
하석민 (수리과학과 2017학번) 6/40
길현준 (2018학번) 3/40
강한필 (전산학부 2016학번) 3/40
문정욱 (2018학번) 3/40
노우진 (물리학과 2015학번) 1/40
윤정인 (물리학과 2016학번) 1/40

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