Archive for the ‘diagrams’ Category

A Power Law


One of my advisees this semester, George Okeowo, investigated the error messages produced by Python, using a corpus of 600000 buggy programs submitted by students to the Computer Science Circles website. The project was focused on writing beginner-understandable versions of error messages, focusing on the most common errors. A side-effect of the investigation was to […]



The diagram above is from a paper of mine which, as I found out today, was published last year! It is in ACM Transactions on Algorithms, although their website still lists the “current issue” as 2010 and they didn’t tell me when it went to press. The paper, joint with Ramki Thurimella, is about using a […]

The Matrix


The Matrix Here is a factoid which might be a nice exercise. Fix integers 1 ≤ q ≤ p. Consider the p×p matrix where the entry in row i and column j is: 1, if i+j mod p is one of {0, 1, …, q-1}; 0, otherwise. This matrix is a cyclic matrix with q […]

2×2 Grids


In conducting research, drawing 2-by-2 grids has some sort of magical power over me. One typical example occurs on page 4 of a paper by me and my colleague Deepc; it looks something like: approximation ratio Packing problems Covering problems k constraints per variable Θ(k) Θ(log k) k variables per constraint n k For me, […]