About

• Name: Alexandra Valentine-Ketchum
• Location: 🇬🇧
• Human Languages: 🇬🇧, 🇯🇵
• Computer Languages: Python, Rust, Javascript, Haskell, C, C++
• Email: snowdrop404 🄰🅃 🄿🅁🄾🅃🄾🄽🄼🄰🄸🄻 🄲🄾🄼

Self-taught programmer. I love safe, secure, fast, and robust code. I enjoy working on hard problems.

Technologies

• Data: XGBoost, scikit-learn, Numpy, Scipy, Pandas, Polars, Matplotlib, Seaborn
• Python Tools: Cython, Numba, Pydantic, Pytest, Mypy, Ruff, uv, Poetry, setuptools, functiontrace
• Dev Tools: Git, Fish Shell, Github Actions, Ubuntu
• Devops: Docker, Kubernetes, Helm, Argo CD
• Distributed systems: Prefect, Dask
• Web: Django, Rocket, HTML, CSS
• Databases: MySQL, SQLAlchemy, Django ORM

Employment

fluidstack.io

• Period: 2025-Present
• Title: Forward Deployed Engineer

chess.com

• Period: 2022—2024
• Titles:
  • Intern (2022/09—2022/10). Give a full-time position half-way through internship, due to performance.
  • Core Chess Engineer (2022/10—2023/12)
  • Senior Engineer (2023/12—2024/11)

I worked in the cheat detection & research team. The precise details of my cheat detection work are under NDA.

• Successfully rewrote a cheat detection system from Perl to Python (wrote 80% of the code). Increased performance 4x. Discovered and fixed multiple bugs. Created complete test coverage with over 1000 tests. Smoothly deployed as a drop-in replacement in production, maintaining bug-for-bug compatibility, and exactly replicating over 100 cheat detection statistics and algorithms.
• Lead development and design of a successful ground-up rewrite of a cheat detection research tool (wrote 80% of the code). Made it work as a distributed system with caching, to enable it to process hundreds of statistics per chess position for hundreds of millions of positions in minutes. Increased performance 150x, even without the cache. Made it highly configurable and flexible to allow experimentation with different cheat detection methodologies. Created a Django frontend, and deployed to production, into the hands of researchers. Lead and mentored a team of 4. Wrote and managed tickets. Worked out requirements. Managed the project and its priorities, and set the short and long-term direction.
• Conducted research and development of a machine learning model to predict how difficult chess positions are for humans. Researched, wrote, documented, extracted thousands features from a C++ program. Integrated the compiled model back in to the C++ program, and went through many iterative improvements on the model. Built a program to empirically verify the model by testing it on chess.com employees.
• Collaborated closely with data scientists and chess experts on cheat detection problems. Implemented, optimised, improved, and spotted bugs with new and existing methodologies. Made my own proposals and conducted my own research on new methodologies. Made many discoveries about various factors influencing cheat detection power.
• Invented a novel modification to a well-known statistical hypothesis test underlying the cheat detection system. Invented novel inputs to use in this hypothesis test, and used them both in combination to significantly improve cheat detection performance.
• Solved various problems with transpositions in a database of chess openings (forming a cyclical graph) that had vexed multiple people (including consultants brought on to tackle the job). Created a library to help navigating and manipulating the data, and numerous scripts to fix the data.
• Served as the go-to person for helping with Python problems, and as a leader on Python best-practices. Wrote and maintained the documentation and guides for working with Python at chess.com. Wrote and maintained the template repo for Python projects. Worked extensively on CI/CD and devex for various Python repos.
• Wrote a library for chess game analysis at scale. Supports using local chess engines, remote chess engines, and proprietary chess.com game analysis software. Makes extensive use of async, websockets, multithreading, and multiprocessing for maximum performance. Used across various Python projects at chess.com.
• Wrote a library providing Python bindings to a C++ library with Cython.
• Ported academic code from a paper for the quantification of multimodal distributions from R to Python. Optimised with numba. Increased performance 10x, and made it maintainable, sane, and verifiably correct with full test coverage.
• Created a chess engine compile optimiser that enumerates different compilers and different compiler flags, and empirically verifies the performance of every resulting binary. Found 3-15% performance increases versus the builds we were using, and uncovered makefile bugs in a popular chess engine.
• Helped write an internal feature flag system, with libraries for Java, Python, Rust, and Typescript.

Contracting

SkySight

• Period: 2024-Present

• Optimising, adding tests, and updating meteorlogical forecasting code to modern standards.

Open Source

Ruff

• [pep8-naming] eliminate false positives for single-letter names (N811 & N814)

Reqsign

• Google Cloud: Add support for impersonated service accounts

Personal Projects

Tanmatsu

Declarative TUI library; bringing modern web layout features to the Unix terminal.

• https://github.com/snowdrop4/tanmatsu
• https://tanmatsu.readthedocs.io/en/latest/

Acorntorrent

Next-generation private BitTorrent Tracker.

• https://github.com/snowdrop4/acornserver

Achievements

• Ranked top 0.08% (~3.2 sd) of the competitive player-base in Europe in Overwatch (4200 SR).
• Ranked top 0.37% (~2.7 sd) of the competitive player-base in Europe in League of Legends (Diamond II) in my first season of play. Placed 4th on the op.gg Europe leaderboard for my character for that season.