Extended Songer Theorem

Every integer minus any permutation of its digits is divisible by nine.

Introduction to Cryptic Crosswords

A few example clues from my favorite type of crossword.

Job Application

Can you solve a puzzle hidden within a cover letter?

Solving 2-CNF-SAT in Linear Time

We discuss the linear-time algorithm for computing the satisfiability of a 2-CNF formula.

H-Polyhedron Boundedness

We determine whether polyhedra can be efficiently checked for boundedness using a fundamental idea from linear algebra.

n×n Chess is EXPTIME-Complete

A brief sketch of the proof that n×nn \times n chess is EXPTIME-Complete.

Songer Theorem

Every integer minus its reversal is divisible by nine.


Coming soon...