以前的笔记，算个索引吧↓


1. The Foundations: Logic and Proofs

2. Basic Structures: Sets, Functions, Sequences, Sums, and Matrices

3. Algorithms

4. Number Theory and Cryptography

5. Induction and Recursion

8. Countings

9. Relations

离散数学结构-Groups and Coding

离散数学结构-半群与群

10. Graph