User:Techit/Knowledge dump

Hello, welcome to Techit's knowledge dump page. Here I will dump as many knowledge as possible for collection in the future use.

Here's the table of contents

__TOC__

Mathematics

Set

Imagine a data array, it's a set. Set is a collection of different stuff. For example A = {1,2,3,4,5,6,7,8,9} or $\text{Slave}=\{\text{Diskette},\text{GameCreator}\}$.

Elements / Members

A stuff in a data set is called "element" or "member", so to write a set notation we use $\in$(in) or $\in ̸$(not in). Let's see some examples below.

$A=\{x|x\in I^{+},-5<x\le 12\}$ or $B=\{x|x\in P,-5\le x\le 23\}$