I remember when I was in high school, there was a chapter in the Math book named “Logic”. We spent about a month dealing with the problems such as “Since A is false, A or B is true, we could know that B is true”. It seems to be very easy to solve this kind of problem. However, if there were hundreds or thousands variables, things are getting difficult.

The post correspondence problem was first introduced by Emil Post in 1946. It was defined as follows: Suppose you have an infinite number of different kinds of dominoes. There are two non-empty alphabet strings on the two sides (top and bottom) of each domino. What you need to do is to place dominoes side by side so that the combination of strings on each side are same.

I plan to implement a basic, tiny and reliable web search engine these days. It was difficult to write a search system all by myself, so I try to use PyLucene. After installing PyLucene on my Ubuntu, I find it a little bit user-unfriendly during the installation. However, this article will show how to install PyLucene.

Sometimes I need to figure out where the XSS script the attacker injected in my website, so I came with an idea I need a tool to scan the malicious scripts automatically. So I wrote anti-XSS, an open source scanning tool for XSS vulnerability.