cybir: Birational geometry of Calabi-Yau threefolds

cybir is a Python package for studying the birational geometry of Calabi-Yau threefold hypersurfaces in toric varieties, following the methods of arXiv:2212.10573 and arXiv:2303.00757.

The package reconstructs the extended Kahler cone (EKC) from genus-zero Gopakumar-Vafa invariants and integrates cleanly with CYTools.

Features:

• BFS-based EKC construction with adaptive GV degree

• Classification of extremal contractions (asymptotic, CFT, su(2), symmetric flop, generic flop)

• Coxeter group construction and orbit expansion for the full birational geometry

• CYTools monkey-patching for seamless integration

• On-demand GV reconstruction for any phase

Table of contents

API Documentation

• cybir API
• cybir.core

Examples

• Survey: All h11=2 Calabi-Yau threefolds
• EKC Construction: h11=2 Example
• EKC Construction: h11=3 Example

Indices and tables

• Index

• Module Index