Gee Law’s Blog
I have heard about λ-calculus as a computational model for long, but never got a chance to have an even recreational look at it. Today’s entry simply records the creating of the parser.
When you open VS2015 Command Prompt from a newly installed instance of Visual Studio 2017 Community, the prompt fails to intialise the variables. Telling you to “make sure either Visual Studio or C++ Build SKU is installed”. Searching the Internet, this seems to be a known and persisting issue. Here I propose an elegant workaround for it.
Base conversion is the conversion between notations of number, and NOT the numbers themselves. I discuss a common mistake on methods of base conversion, and a common mistake in thinking about ‘base conversion’ in computer programs.
Lagrange’s four-square theorem is a beautiful result in number theory. However, to the best of my knowledge, I haven’t encountered it often in theoretical computer science. Today’s entry discusses two interesting stories related to this theorem.
姚栋想要知道如何在 Windows 中使用命令解压缩 ZIP 文件夹。他表示如果要用 .NET Framework 提供的 API，则需要 4.5，但环境要求 4.0；如果用 PowerShell Expand-Archive 命令，则需要 5.1，但环境只允许 2.0；想用 cmd，但不知道怎么做。然而应该时刻记住：Windows 自带的 GUI 实际上经常是 COM 的图形版，在 COM 中寻找几乎总是可以找到你想要的图形操作的命令版本。
Starting from the classic puzzles of finding patterns in a sequence, this entry explores the framework to define persuasive patterns. The framework is found to be quite self-contained in the sense that it is ‘asymptotically invariant’ to the choice of ‘language of expression’. The only short-coming of this framework is that it works only for computable sequences, yet the process of pattern discovery is incomputable.