FDB Applet

A computational tool for the representation theory of gentle, string, and (in the future) biserial algebras

Online version → GitHub repository →

About, installation & license

Version: 1.0  ·  Release date: June 1, 2026

Background & motivation

The FDB Applet has been developed exclusively as a computational tool intended to facilitate research on problems arising in the representation theory of gentle algebras and string algebras. The long-term objective of this project is to incorporate additional functionalities relevant to the study of biserial algebras — one of two motivations behind the letter "B" in "FDB," standing for "Finite-Dimensional Biserial."

In developing the FDB Applet, I benefited substantially from the highly valuable and elegant FD Applet, developed and released in 2023 by Haruhisa Enomoto. I wish to expressly acknowledge the significant conceptual, structural, and practical inspiration provided by the FD Applet — this project owes a considerable intellectual and organizational debt to it.

The FDB Applet contains portions translated or adapted from the FD Applet, released under the MIT License. This is the second motivation for the letter "B": the present software may be viewed, in a broad conceptual sense, as a secondary branch or extended continuation of the original framework.

Why a new applet?

Noting that the FD Applet did not appear to have undergone substantial updates since mid-2023, I contacted the original developer to propose incorporating additional functionality. After some correspondence, it became clear that the July 2023 version might not see further development. This motivated me to implement functionality addressing developments that have emerged in recent years — particularly around the study of bricks — which occupy a central position in my ongoing research program. I hope this applet contributes to future collaborative initiatives and evolves into a useful computational resource for the community.

The development process initially involved translating substantial portions of the FD Applet codebase from Kotlin into Python with the assistance of Claude, followed by the integration of additional computational functionality and extensions. Both the software development process and the accompanying documentation benefited significantly from the foundational contribution of the FD Applet and from technical assistance from Claude.

The current version remains under active development and may contain mathematical inaccuracies, technical defects, or partially implemented functionality. Some tabs or features may not yet perform their intended operations, though such functionality is expected in forthcoming versions.

If you identify any mathematical inaccuracies, computational inconsistencies, or technical malfunctions, please contact the developer, Kaveh Mousavand, at kaveh.mousavand@oist.jp.

Installation instructions

The online version is useful for simpler tasks, but the installed version is significantly faster for heavier computational tasks. The latest version, along with detailed step-by-step installation instructions in the repository's README, is available on GitHub.

Quick start

For users already comfortable with a command line, the entire desktop installation reduces to five steps (assuming Python 3.10+ is already installed):

unzip FDB-Applet.zip          # available on GitHub
cd FDB-Applet
python3 -m pip install fastapi uvicorn
python3 -m uvicorn fd_applet_python.server:app --port 8000
# then double-click fd_applet_python/fd_applet_visual.html

On Windows, replace python3 with python. A platform-by-platform walkthrough, including download links and troubleshooting, is in the README on the FDB GitHub repository, where the latest updates appear.

License