Poset

Partially ordered sets and Directed graphs are two sides of the same coin.

This repo shows how to implement a Poset in Java. See http://blog.bytecode.tech/how-to-implement-a-poset-in-java/ for a detailed explanation.

Tech stack

• Java 11
• Junit 5 (unit test library)
• jqwik (property based tests library)
• assertj (test assertions library)
• graphviz (graph visualization library)

Techniques

Here's a list of some of the techniques used in this repo:

• Use of the Observer pattern to calculate the transitive expansion of the incidence matrix
• Definition of property based tests (PBT) to verify the correctness of the Poset implementation
• Implementation of a jqwik Arbitrary to produce random permutations with replacement in order to generate Posets for the PBT
• Implementation of a Java Set

How to run the application

The entry point is a Main class that creates a Poset and iterates over the elements in topological order.

• mvn clean test
• mvn exec:java -Dexec.mainClass="fjab.poset.Main"

Graphviz

Graphviz is used to generate graphs based on .dot files.

Here's an example of how to use it:

dot -Tpng poset_graph.dot -o outfile.png

The file poset_graph.dot can be found on src/main/resources