# Visualization of Constraint Handling Rules: Semantics and Applications

## TL;DR

This paper introduces an animation extension for Constraint Handling Rules (CHR) called $CHR^{vis}$, which embeds visualization features into CHR programs to aid understanding, debugging, and illustrating program execution.

## Contribution

It provides the operational semantics and correctness framework for $CHR^{vis}$, enabling animated visualization of CHR program execution.

## Key findings

- $CHR^{vis}$ successfully animates CHR program executions.
- The extension improves debugging and understanding of CHR programs.
- Applications demonstrate practical benefits of visualization in constraint programming.

## Abstract

The work in the paper presents an animation extension ($CHR^{vis}$) to Constraint Handling Rules (CHR). Visualizations have always helped programmers understand data and debug programs. A picture is worth a thousand words. It can help identify where a problem is or show how something works. It can even illustrate a relation that was not clear otherwise. $CHR^{vis}$ aims at embedding animation and visualization features into CHR programs. It thus enables users, while executing programs, to have such executions animated. The paper aims at providing the operational semantics for $CHR^{vis}$. The correctness of $CHR^{vis}$ programs is also discussed. Some applications of the new extension are also introduced.