Others

Technical memo

  • Geometric interpretation of gradient-based scheduler, 2006 [pdf]

    • When I was a phd student, my advisor (Prof. Song Chong, KAIST) suggested me to work on the interpretation of the gradient-based scheduler which was then the hottest wireless scheduler. This memo interprets the gradient-based scheduler from a different angle (rather than the myopic derivation based on the maximization of increment of utility function). This memo has never been published, and perhaps is straightforward, but still seems to be an interesting view of gradient-based scheduler.

  • A note on the number of maximum matchings in odd-sized rings [pdf]

    • While I was working on the schedulability in one-hop interference model which necessarily involves the matching polytope, I needed to find the number of maximum matchings in some special graphs. This may be a good exercise problem in elementary graph theory, or discrete math as it contains the idea of recursion to derive a function of natural numbers.

  • On the signwise convergence in distributed consensus problems [pdf, to be updated]

    • Convergence typically indicates some sequence eventually ends up with a certain fixed "value" (of course, probabilistic convergence is defined differently in several ways). In some consensus problems where identical binary decision has to be made all over the system, only the signs of sequences evolving separately in every node in the system matter. This memo attempts to compare the signwise converge with conventional valuewise convergence.

Math

  • The Cauchy-Schwarz Master Class (An Introduction to the Art of Mathematical Inequalities) by J. Michael Steele (2004): Contain various elementary (both failing and working) approaches to the proofs of important mathematical inequalities including Cauchy-Schwarz, AM-GM, Jensen, Holder, Hilbert, Hardy, etc. and other mathematical statements applying these inequalities. Steele's explanation just shows the essence of mathematical reasoning, and he is generally thought to be a very good writer. I really enjoyed this book mainly for fun, but as a bonus, in some research, it helped me. I sometimes solve exercise problems in this book, again just for intellectual joy.

  • Proofs from THE BOOK by Martin Aigner and Gunter M. Ziegler: The legendary Paul Erdos didn't believe in God, but believed in The Book (that only God knows) that contains the perfect proofs for mathematical theorems. This belief is believed to be influenced by George H. Hardy's dictum that there is no permanent place for ugly mathematics. This book contains some simple but elegant proofs of mathematical theorems in many different areas of mathematics. I only read a small part of it, but this book is always on my to-read list.


Hobbies

  • Sports

    • Tennis

      • used to play a lot during 2012~2016, but not much these days

    • Pingpong

      • I have a decent pingpong table (that folds) in my office

    • European Football

      • played in undergraduate football club in KAIST

      • represented KAIST in annual KAIST-Postech science (and sports:) war

      • big fan of FC Barcelona since around 98-99

      • big fan and (very small) shareholder of Daejeon Citizen FC which plays more in the second division of K-League these days

      • used to be a fan of Arsenal when Dennis Bergkamp and Thierry Henry played charm football but not these days because of Arsene Wenger's long-time policy that rules out big signings (which I believe eventually limited their growth as a big club)

    • American Football

      • fan of New England Patriots

      • play catch with my sons (the older one is much better than I am, throwing a perfect spiral)

  • Music

    • enjoy any kind of music, but these days, mainly Classic, and also HipHop songs (mostly in the car) on my son's playlist