Hierarchy of Parameters (HOPS)

A database of structural graph parameters, their properties, and relationships in parameterized complexity theory.

View the Website

About

HOPS provides a comprehensive reference for researchers working with graph parameters. The database includes:

• Parameter definitions (treewidth, pathwidth, clique-width, etc.)
• Bounding relationships between parameters
• References to relevant publications
• Visual diagrams showing parameter hierarchies

Repository Structure

parameters/
├── code/           # Rust database and content generator
├── handcrafted/    # Manual website content and bibliography (main.bib)
├── web/            # Generated Hugo website (git submodule)
├── docs/           # Project documentation
└── scripts/        # Utility scripts

Quick Start

Prerequisites

• Rust (latest stable)
• Graphviz (for diagram generation)
• Hugo (for local website preview)

Generate the Website

cd code
cargo run all

Preview Locally

cd web
hugo server

Contributing

Contributions are welcome! You can help by:

• Adding parameters - Edit code/src/collection.rs using the builder API
• Adding relations - Document bounds between parameters with source references
• Improving content - Enhance descriptions or add missing information
• Reporting issues - Submit bug reports or feature requests

Documentation

• Contributing Guide - How to add parameters and relations
• Codebase Overview - Technical architecture and module structure

Feedback

• GitHub Issues - Bug reports, feature requests
• Feedback Form - Anonymous feedback

Related Work

This project builds upon earlier work in the field:

• Parameterized Hierarchy (2013-2019) by Manuel Sorge
• Comparing Graph Parameters by J. Ch. B. Schröder
• Comparing 17 Graph Parameters (2010) by Róbert Sasák

License

MIT License - Copyright (c) 2023-2026 Václav Blažej & contributors