钱钟书先生曾经说过，巴黎就像一座围城，外面的人想进来，里面的人想出去。在巴黎安顿下来，走遍巴黎的大街小巷之后，很自然地，就该好好盘算一下 8 月份要去哪里度假了。
In the March, a group of researchers published a paper on preprint  on the investigation of the possible correlation between the ABO Blood Group and the COVID-19 Susceptibility. By comparing the blood group distribution of the 2173 patients in Wuhan in 2019-2020 with that of normal people in 2015, they found a significantly increased risk of blood group A for COVID-19 and a decreased risk of blood group O.
In my opinion, such study is quite problematic and the conclusion can not be regarded as solid. First, before the Wuhan lockdown, roughly half of the people have left for the Lunar-New-Year family reunion. Since they come from different proviences, the blood group distributions might be different. Second, not all the Wuhan residents are exposed to the virus. Normally such virus is spreading in several communities. A solid conclusion can only be obtained by comparing the blood group distributions of the infected people and of the exposed people. I have to admit, such study is extremely difficult, if not impossible, to achieve. Nonetheless, I am not going to propose a better research. I am just questioning their conclusion.
In this blog, I would like to build a toy Monte-Carlo Model to simulate the evolution of blood group distribution. This work is just to test my ability of coding a MC program.
居家工作期间比较无聊，就作作 Guardian Weekly 上的 Futoshiki 和 Sudoku 解闷。这篇文章详细的记录了我解决 2020 年 4 月 17 日那期杂志的 Futoshiki 的解题过程。