Monthly Archives: February 2007

Form or function?

Why are there pieces of wood sticking out of the walls? Is it decoration or do they serve a purpose?
mosque
This is a picture of The Great Mosque of Djenne in Mali, the largest mud structure in the world.

The Chicago Cultural Center has an exhibition of African art. Most of it was the usual fare of masks and clothing with feathers. One thing that captured my interest was a short video about a mosque in Mali. The mosque is made out of sun-dried bricks and it is covered by mud. Every year the people of the town gather to replenish the walls with fresh layers of mud because the rain washes the mud off. The video showed how the work is done. The pieces of wood sticking out serve as scaffolding. People climb on them, slap mud on the walls, and spread it evenly with their hands. I did not know that.

The Cultural Center always has interesting stuff going on and it is free.

Picture by Don Meliton. Other photos.

Me vs. the Tribune (sort of)

The Tribune Company has a free daily publication called Red Eye. Besides sports, the weather, and celebrity news, Red Eye has a Sudoku puzzle. The Tribune owns a radio station too. In a weird case of synergy, every Friday a DJ from the radio station solves the Sudoku on the air. The DJ competes against a challenger from the general public who solves the Sudoku faster.

Last Friday, I was the challenger. I hoped to be on the air and mention the Bisonarium initiative. The DJ did not come that day so I ended up solving the Sudoku in a cubicle in one of the Tribune offices. I solved the Sudoku in 41 minutes, a really bad time for me but it was OK because I was ten minutes faster than the DJ.

What I took with me from the experience besides Red Eye swag is a new approach for solving a Sudoku. It could have been the change of scenery and medium (pen and several paper copies as opposed to a computer) that prompted me to try a new idea.

Brute force. Brute force is the nickname for solving a problem by trying all of the possibilities.
sudoku

This how it started.


sudoku

Got stuck because the more complex tricks I know did not work. The blue pairs of numbers show boxes where the answer can only be one of the two (4 or 9 in upper right box). I kept seeing in my head the page with a picture of the guy who took 91 minutes to finish. I did not want to be him. I was in a competition and losing was unacceptable. Looking at the board, I decided to gamble. I chose a pair (let’s call it the original pair) and arbitrarily chose one of the two possible values and continued to solve the puzzle. If the solution I had did not make sense then I knew that I chose wrong and the other possibility in the original pair had to be right.

I repeated this method three times and solved it 10 minutes faster than the DJ. How freakonomic is that?


sudoku

This is how it looked in the end. When I got home I tried the method again on the extra hard Sudoku at About.com. The conclusion I arrived at is that choice of the original pair to fork from has to be smart. It is choosing a pair where either value would lead for the most consequences. In the case above, the pairs (3,4) and (4,3) in the central 3×3 box is the best pair. I hope I was clear.