Inside 206-105

Existential Pontification and Generalized Abstract Digressions

April, 2013

The Difference between Recursion & Induction

Recursion and induction are closely related. When you were first taught recursion in an introductory computer science class, you were probably told to use induction to prove that your recursive algorithm was correct. (For the purposes of this post, let us exclude hairy recursive functions like the one in the Collatz conjecture which do not […]

  • April 27, 2013

Kindle is not good for textbooks

Having attempted to read a few textbooks on my Kindle, I have solemnly concluded that the Kindle is in fact a terrible device for reading textbooks. The fundamental problem is that, due to technological limitations, the Kindle is optimized for sequential reading. This can be seen in many aspects: Flipping a page in the Kindle […]

  • April 15, 2013

A Zerocoin puzzle

I very rarely post linkspam, but given that I’ve written on the subject of anonymizing Bitcoins in the past, this link seems relevant: Zerocoin: making Bitcoin anonymous. Their essential innovation is to have a continuously operating mixing pool built into the block chain itself; they pull this off using zero-knowledge proofs. Nifty! Here is a […]

  • April 11, 2013

A classical logic fairy tale

(Selinger) Here is a fairy tale: The evil king calls the poor shepherd and gives him these orders. “You must bring me the philosophers stone, or you have to find a way to turn the philosopher’s stone to gold. If you don’t, your head will be taken off tomorrow!” What can the poor shepherd do […]

  • April 7, 2013


Humbly presented for your consideration: Exhibit A, an NDSEG essay that did not get accepted; Exhibit B, an NDSEG essay that did get accepted. It’s pretty cool what making a statement more focused can do. (See also Philip Guo’s page on the topic.)

  • April 5, 2013

Resource limits for Haskell

Last week, I made my very first submission to ICFP! The topic? An old flame of mine: how to bound space usage of Haskell programs. We describe the first iteration of a resource limits system for Haskell, taking advantage of the key observation that resource limits share semantics and implementation strategy with profiling. We pay […]

  • April 2, 2013