In this post I’ll show you how to solve the vertex coloring problem to optimality using linear programming. Since the problem is NP-complete, there is no algorithm which can solve any problem instance in deterministic polynomial time. In a former post, I used constraint programming to find an optimal (minimal) vertex coloring. A popular greedy… Read more Vertex Coloring using ILP

# Category: programming

## The Tennis Court Problem (TCP)

I owe this task to Ruedi, a regular tennis player. The Tennis Court Problem (TCP) is about the following task. At the beginning of outdoor tennis, the court lines must always be cleaned first. The sweeping set is often placed in one of two typical locations, usually either on one side of the net or… Read more The Tennis Court Problem (TCP)

## Solving Happy Cubes® on A micro:bit

In this post I’ll demonstrate the results of my most recent fun project on the micro:bit: An app to solve Happy Cubes®, a set of puzzles created in 1986 by the Belgian toy inventor Dirk Laureyssens. My kids were playing with these cubes and I was wondering, if the micro:bit could solve these cubes in… Read more Solving Happy Cubes® on A micro:bit

## Map Coloring Problem

This is a similar post as the one on Graph Coloring. However, this in this post I show an application of the graph coloring problem, allowing us to answer practical questions using graph theory. In this post we’ll first tackle a map coloring problem manually, then we’ll use a MiniZinc constraint programming script to validate the solution found.

## Graph Coloring Problem

A node coloring is valid or admissible if any two adjacent nodes do not have the same color. If a graph is colorable, there is a smallest number such that the graph is node colorable. This number is called the chromatic number of the graph and is usually denoted by . The problem to identify… Read more Graph Coloring Problem

## Happy Birthday Duino

In this post I’ll show you the simplest setup to generate synthetic sound using an Arduino Pro Mini. Of course you can also run it on a Leonardo or on an Arduino UNO R3. The project is inspired from a project from the official arduino project hub and you can get the sourcecode here. What… Read more Happy Birthday Duino

## TSP Miller-Tucker-Zemlin Subtour Elimination Constraint

In this post we want to try to provide a solution to solve the Traveling Salesman Problem (TSP) using linear programming. The post is based on this excellent video from Mr. Michel Bierlaire at the EPFL. A good written documentation of the Miller Tucker Zemlin Constraint can be found here. What is a TSP? The… Read more TSP Miller-Tucker-Zemlin Subtour Elimination Constraint

## An Arduino based Math Trainer

In this post I’ll show you how to build an arduino based math training console based on simple standard components. The app is suitable for training math in lower and middle school. It allows configuring difficulty level as well as operations and lets the player choose the correct result from a selection of 4 outcomes… Read more An Arduino based Math Trainer

## Deploy Python UI Apps including Java Business-Logic

In this post you’ll learn how to deploy a python application in the form of a directory which can be distributed as an archive or as a single executable file. This is the last of three posts on a series about UI development in python embedding Java based business logic and shows you a concept,… Read more Deploy Python UI Apps including Java Business-Logic

## Embedding Java Logic into a Python Application

In this post I’ll demonstrate how to embed logic provided by a java application into a python PyQt5 UI based application. The motivation for this project arose from the need to be able to port legacy code in the form of an old Eclipse Rich Client Platform application to a contemporary technology with as little… Read more Embedding Java Logic into a Python Application