Archives for November 2011

November 2011 (4)
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PCPlus 299: Answering difficult questions

I’d just read a book called Introduction to the Theory of Computation by Michael Sipser and found it fascinating enough that I tried to encapsulate what NP-complete means in a 2000-word essay for October 2010’s issue. Was I successful? You’ll have to read it to find out. In essence, I talk a bit about big-Oh and show that algorithms that have exponential or factorial big-Oh expressions are terrible to implement since they rapidly get to the point where it just takes too long to do anything. I then...


Blog issues. Or GraffitiCMS issues. Or GoDaddy issues.

Apologies to all if you saw a whole bunch of posts appearing and disappearing in the past hour. I’m having – all of a sudden – extreme problems with publishing a blog post from Windows Live Writer to this blog, which is hosted on GoDaddy. This first happened on November 5, but I thought it was a transient issue and ignored it. And then over the weekend I wrote the “adding parentheses” post but it would not publish, no matter what. I finally published it just now with...


Postfix to infix, part 2: adding the parentheses

Once upon a time (all right, it was in May 2010), I wrote an article for PCPlus about generating all possible arithmetic operations with the standard four operators. You can read the article here . After I’d written it, I wrote a blog post about how easy it was to convert the RPN form ( Reverse Polish Notation ) of the expressions I was generating into the standard algebraic or infix form. You can read that post here . (Note that this post will make more sense if you read these two articles first...


PCPlus 298: Solving Rubik’s Cube

Ah, memories, memories. For September 2010’s issue I wrote about how to solve Rubik’s Cube , and it allowed me to revisit my days at Kings’, London, when I first came across the puzzle. Back in those days (and probably even now), the Maths Society at Kings had a fun weekend away in Windsor Great Park where we’d have talks about recreational mathematics. (Yes, I know, many people don’t think “recreational” and “mathematics” can be in the same sentence, but bear with me here.) Of course, it was an...