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ElMatiOfficial/README.md

Sebastian Mateus

Senior AI/ML Engineer at Nequi (Grupo Bancolombia), pre-training foundation models on customer transaction sequences. 8+ years shipping production ML. Based in Colombia 🇨🇴.

I'm most interested in the gap between what a model appears to do and what it actually does — evaluation that survives scrutiny, agent tool-use that earns its place, and systems whose failure modes are written down before someone finds them.

Full portfolio & research →


Selected work

RealH — Proof-of-personhood and content provenance using W3C Verifiable Credentials. Ed25519 signing, did:web, public JWKS for offline verification. The README opens with four specific reasons not to trust it in production, because a reference implementation that hides its threat model is worse than none. TypeScript · CI · CodeQL · gitleaks · ADR on JCS canonicalization

Kaggle write-ups — 19 competitions, each documented as a short paper. Includes a provenance ledger that states, per competition, exactly which submissions were my own work and which were not — verified by diffing my final submissions against the public notebooks they came from. 5 of 19 were substantially original; the ledger says which, and names every upstream author.

EML translator — Library for translating mathematical expressions to and from Exp-Minus-Log trees (Odrzywołek's primitive). Forward/inverse translation, complex-branch evaluation, exhaustive identity search. Python · 116 tests · MIT

EML research POC — Wires those operations into Claude as tool-use and benchmarks whether it helps. The honest answer, reported in the README: on calculus and algebra the agents largely ignore the EML tools in favour of sympy. It earns its keep only on translate/evaluate/verify tasks.

barrio-mapper — Maps the small independently-owned businesses of a neighbourhood — tiendas, droguerías, ferreterías — while filtering out chains. Three-signal chain detection with an auditable rejection log. Tested in Medellín; runs in the browser. Python · tests · CLI + browser app


What I work on

Production ML — foundation model pre-training on transaction sequences · credit risk (PD/LGD, loss-rate forecasting, IV/WoE, Platt calibration, SHAP-driven adverse-action reasons) · recommender systems

Agentic systems — tool-use design and evaluation · structured output · multi-step orchestration · guardrailed tool access · agent security (multi-step tool attacks)

Evaluation & observability — offline eval sets wired into CI · faithfulness and LLM-as-judge · embedding drift detection · PSI monitoring · Langfuse tracing

Stack — Python · SQL · PyTorch · scikit-learn · XGBoost · LightGBM · Hugging Face · BigQuery · dbt · Airflow · FastAPI · MLflow · AWS · Docker · Terraform · GitHub Actions


Elsewhere

Portfolio · LinkedIn · Kaggle · TEDx talk

Trilingual (ES/EN/PT) · Mentored 13+ engineers

Pinned Loading

  1. EML-Mathematical-Translator-for-AI EML-Mathematical-Translator-for-AI Public

    Translate mathematical expressions to and from EML (Exp-Minus-Log) trees, the single-operator primitive for elementary mathematics from Odrzywolek (arXiv:2603.21852). Built for AI/ML researchers.

    Python

  2. EML-Research-POC EML-Research-POC Public

    Research POC: Odrzywolek's EML (Exp-Minus-Log) primitive wired into Claude Code as a tool-use capability. 21/21 math benchmark + 8/8 Riemann Hypothesis sub-investigation.

    Python

  3. realh realh Public

    Open-source proof-of-personhood and content-provenance tooling. Issues W3C Verifiable Credentials signed with Ed25519; verifiable offline via did:web + JWKS.

    JavaScript