Shortest Path Problem

Problems like finding the optimal route between two cities on a complex road network, or transmitting a message between two nodes across a sprawling computer network, are all instances of the shortest path problem. ...

2018-12-18 · Updated: 2025-06-22 · 7 min

The Assignment Problem

Given $n$ workers and $n$ jobs, and the cost $c_{ij}$ to train the $i$-th worker for the $j$-th job, find an assignment of one worker to each job which minimized the total training cost. ...

2018-12-16 · 5 min

Ramsey Number

Problem: What is the smallest integer $n$ such that in any group of $n$ people, where each pair consists of either mutual friends or mutual strangers, there must be a subgroup of three mutual friends or three mutual strangers? ...

2018-12-13 · Updated: 2025-06-11 · 2 min

Catalan Number

In combinatorial mathematics, the Catalan numbers form a sequence of natural numbers that occur in various counting problems, often involving recursively-defined objects. ...

2018-12-05 · 6 min

Stirling Number

This note explores the combinatorial problem of distributing balls into boxes, which provides a natural introduction to Stirling numbers of the first and second kind. ...

2018-11-29 · Updated: 2025-06-23 · 3 min

Hamming Code

It is extremely difficult, and often impossible, to prevent errors when data are stored, retrieved, operated on, or transmitted. ...

2018-11-19 · Updated: 2025-04-20 · 6 min

哥德尔不完备定理

Any mathematical system containing all the theorems of arithmetic is an incomplete system. ...

2018-11-05 · 4 min