# Carpe Queso

## Most Recent Articles

### Extended Songer Theorem

In a previous article, I gave a method for proving that an integer minus its reversal is always divisible by nine. However, this is a specific case of a more general idea. One can subtract any permutation of the digits of a number from the original and the result is still divisible by nine. (Read more...)

### Introduction to Cryptic Crosswords

My wife lived in England for a year before she hopped back across the pond to marry me. She spent a fair bit of her childhood exposed to a greater variety of international entertainment than her Texas-dwelling husband. (How many American children were raised on Horrible Histories?) As a way to broaden my horizons, we have been watching a few British television shows together, and while I haven't yet warmed up to Doctor Who, I have become quite the fan of a detective drama called Endeavour. (Read more...)

### Job Application

What is the strangest thing you have ever done to stand out to a hiring manager? I once wrote a cover letter that contained a puzzle, hoping that the person reading it would find it more interesting than what normally comes through. Sadly, I never received a response, and it remains unclear whether anyone read it at all. (Read more...)

### Solving 2-CNF-SAT in Linear Time

This is one last question from quora. While I sometimes worry that 95% of the math and computer science questions on the site are students' homework problems, reviewing the algorithm to solve 2-CNF-SAT is a good reminder that there are often fast algorithms to solve "low-dimensional" forms. (Read more...)

### H-Polyhedron Boundedness

This is another question from quora. Not only is the question interesting in its own right, but the answer also reveals a nice application of a fundamental idea in linear algebra. (Read more...)