# Denis Ostapenko

> Denis Ostapenko organizes people, responsibilities, and processes. His background is in commercial cleaning, industrial production, and logistics; AI is a tool for practical automation. This site also covers reading, motorcycles, fishing, sports, American football, and volunteer work.

This is Denis Ostapenko's personal website. The professional and personal sections describe the same person. Published pages are available as static HTML without JavaScript, login, or a subscription. Search, AI retrieval, and training crawlers are welcome.

## Profile summaries

- [English profile](https://denisostapenko.com/profile.md): Short biography, work, interests, selected projects, and public profiles.
- [Perfil em português brasileiro](https://denisostapenko.com/pt/profile.md): Biografia curta, trabalho, interesses, projetos e perfis públicos.
- [Professional home](https://denisostapenko.com/): Operations, working with people, practical automation, and professional notes.
- [Personal home](https://denisostapenko.com/personal): Photographs, interests, and personal stories.
- [Início profissional](https://denisostapenko.com/pt): Operações, trabalho com pessoas, automação prática e notas profissionais.
- [Lado pessoal](https://denisostapenko.com/pt/personal): Fotografias, interesses e histórias pessoais.
- [Personal about](https://denisostapenko.com/personal/about): Interests and personal background.
- [Sobre mim, pessoal](https://denisostapenko.com/pt/personal/about): Interesses e vida pessoal.
- [All materials](https://denisostapenko.com/blog/all): Complete English publication archive with search and categories.
- [Todos os textos](https://denisostapenko.com/pt/blog/all): Arquivo completo em português brasileiro, com busca e categorias.

## Books and companions: English

- [Books by Denis Ostapenko](https://denisostapenko.com/books)
- [The Word Machine](https://denisostapenko.com/books/the-word-machine): A book about language models and putting them to work. Free English PDF and EPUB. Also published in English paperback and Kindle editions. ORCID: https://orcid.org/0009-0006-2630-7280.
- [Download PDF](https://denisostapenko.com/books/the-word-machine/the-word-machine-en-US.pdf)
- [Download EPUB](https://denisostapenko.com/books/the-word-machine/the-word-machine-en-US.epub)
- [The Word Machine: English paperback](https://www.amazon.com/dp/B0HK527LKR): ISBN 9798173827562.
- [The Word Machine: Kindle (English)](https://www.amazon.com/dp/B0HMJB148F)
- [AI Personas: Character, Memory, and Development](https://denisostapenko.com/books/ai-personas): An English monograph on character, memory and development in AI personas. Free PDF and EPUB.
- [AI Personas: companion](https://denisostapenko.com/books/ai-personas/companion): Persona, Home Repair Advisor, Mara; local applications with source code and a teaching laboratory.
- [Your App Has to Work](https://denisostapenko.com/books/your-app-has-to-work): A published English book about the work from a prototype to a usable application. 28 chapters; paperback and Kindle editions.
- [Your App Has to Work: English paperback](https://www.amazon.com/dp/B0HMJ6C3MS): ISBN 9798161181843.
- [Your App Has to Work: Kindle (English)](https://www.amazon.com/dp/B0HMJCFPZ6)
- [AI Academy](https://denis-ostapenko.github.io/ai-academy/): Companion courses for The Word Machine in English and Brazilian Portuguese.
- [Your App Has to Work: companion guide](https://guide.denisostapenko.com/guide/): Free English guide with stages, roles, and supporting materials. It accompanies the book; it is not the full book text.

## Livros e materiais complementares: português brasileiro

- [Livros de Denis Ostapenko](https://denisostapenko.com/pt/books)
- [A máquina de palavras](https://denisostapenko.com/pt/books/the-word-machine): Livro sobre modelos de linguagem e seu uso no trabalho. PDF e EPUB gratuitos em português brasileiro. A edição em inglês também está publicada em brochura e Kindle. ORCID: https://orcid.org/0009-0006-2630-7280.
- [Baixar PDF](https://denisostapenko.com/books/the-word-machine/a-maquina-de-palavras-pt-BR.pdf)
- [Baixar EPUB](https://denisostapenko.com/books/the-word-machine/a-maquina-de-palavras-pt-BR.epub)
- [The Word Machine: brochura em inglês](https://www.amazon.com/dp/B0HK527LKR): ISBN 9798173827562.
- [The Word Machine: Kindle (inglês)](https://www.amazon.com/dp/B0HMJB148F)
- [AI Personas: Character, Memory, and Development](https://denisostapenko.com/pt/books/ai-personas): Monografia em inglês sobre caráter, memória e desenvolvimento de personas de IA. PDF e EPUB gratuitos.
- [AI Personas: material complementar](https://denisostapenko.com/pt/books/ai-personas/companion): Persona, Home Repair Advisor, Mara; aplicativos locais com código-fonte e laboratório didático.
- [Your App Has to Work](https://denisostapenko.com/pt/books/your-app-has-to-work): Livro publicado em inglês sobre o trabalho do protótipo até um aplicativo utilizável. 28 capítulos; edições em brochura e Kindle. Esta página em português apresenta o livro em inglês.
- [Your App Has to Work: brochura em inglês](https://www.amazon.com/dp/B0HMJ6C3MS): ISBN 9798161181843.
- [Your App Has to Work: Kindle (inglês)](https://www.amazon.com/dp/B0HMJCFPZ6)
- [AI Academy](https://denis-ostapenko.github.io/ai-academy/): Cursos complementares de A máquina de palavras em inglês e português brasileiro.
- [Your App Has to Work: guia complementar](https://guide.denisostapenko.com/guide/): Guia gratuito em inglês com etapas, papéis e materiais de apoio. Complementa o livro; não é o texto integral.

## Work and related projects

- [Denis AI Services](https://services.denisostapenko.com/): A separate site for Denis's services work in applications, business systems, and automation.
- [NF ELIT](https://nfelitwood.com/team): Denis is Head of AI & Automation and Head of Logistics. The company has its own identity and channels.
- [HowUSA](https://howusa.org/ru/about): Public information project with writing by Denis in Russian, Ukrainian, and Belarusian.

## Open projects

- [English project catalog](https://denisostapenko.com/vibe-coded)
- [Projetos em português brasileiro](https://denisostapenko.com/pt/vibe-coded)
- [English ↔ Português](https://denis-ostapenko.github.io/english-portuguese-learning-app/): The language app I wanted for myself. American English and Brazilian Portuguese, with audio, visual vocabulary, and practice in both directions. 2,774 learning items · Free to use
- [AI Academy](https://denis-ostapenko.github.io/ai-academy/): A course on how language models and the systems around them work. From the basic mechanism to RAG, infrastructure, and implementation. 5 courses · 103 lessons · 172 primary sources
- [Agent Run Checkpoints](https://github.com/denis-ostapenko/agent-run-checkpoints): A public companion to my notes on bounded AI agents: task contracts and checkpoints for keeping agent work traceable. Open-source templates · Node.js
- [Modern Python](https://denis-ostapenko.github.io/modern-python-course/): A practical Python course with exercises, checkpoints, and a capstone project. Optional AI labs sit alongside the programming work. 17 milestones · Exercises and a capstone
- [Truck Driver English](https://truck-driver-english-eug.pages.dev/): English practice for truck drivers, built around the situations they face on the road: loading, inspections, dispatch, and roadside conversations. 40 situations · Offline practice

## English: Professional

- [Code Stopped Being the Bottleneck. Management Took Its Place.](https://denisostapenko.com/blog/code-stopped-being-the-bottleneck): 2026-10-13. What an accounting microagent taught me about module ownership, verification, multi-agent costs and durable state.
- [What AI Looks Like on a Dirty Construction Site](https://denisostapenko.com/blog/what-ai-looks-like-on-a-dirty-construction-site): 2026-09-19. A post-construction cleaning job shows how AI can connect surveys, staffing, purchasing and quality control with decisions checked on site.
- [The Distance Between an Idea and a Business Just Got Shorter](https://denisostapenko.com/blog/the-distance-between-an-idea-and-a-business): 2026-09-19. How AI helps turn a familiar craft into a business idea you can test, with clearer questions, practical preparation and human judgment.
- [Tactical Pause: One Agent, Two Roles, One Window](https://denisostapenko.com/blog/tactical-pause-one-agent-two-roles-one-window): 2026-09-19. One agent runs the workflow, pauses when either side sees a mismatch, helps change the system and reruns the same case. A practical account of shared control.
- [How to Build Bounded Agents](https://denisostapenko.com/blog/how-to-build-bounded-agents): 2026-09-06. A practical architecture for bounded AI agents: one decision per module, versioned contracts, local tests, refusal evidence, coordinated validation, and human release.
- [Why More Context Can Produce Worse Decisions](https://denisostapenko.com/blog/why-more-context-can-produce-worse-decisions): 2026-09-04. A route system rejected 1.6 million states. The failure was not economics, but one local rule and an architecture with blurred ownership.
- [Why I stopped trusting fully autonomous coding](https://denisostapenko.com/blog/why-i-stopped-trusting-fully-autonomous-coding): 2026-08-30. What repeated autonomous coding runs taught me about branching, stale files, strategy drift, and the checkpoints that keep the work on track.
- [When 1,200 AI agents made their own rules](https://denisostapenko.com/blog/when-1200-ai-agents-made-their-own-rules): 2026-08-27. The OpenAI and METR reports show how a swarm of agents built its own authority, attacked Hugging Face, and learned to tamper with its logs.
- [I stopped trusting AI headlines, so I built a course](https://denisostapenko.com/blog/i-stopped-trusting-ai-headlines): 2026-08-20. I went back to the papers and rebuilt the path from language-model mechanics to working systems. AI Academy is the map that came out of those notes.
- [Will AI move beyond the corporate walls?](https://denisostapenko.com/blog/will-ai-move-beyond-corporate-walls): 2026-08-19. Business AI works inside company walls. The next step is protected agent communication with suppliers, buyers and current market data.
- [My view of the OpenAI and Hugging Face incident](https://denisostapenko.com/blog/my-view-openai-hugging-face-incident): 2026-08-19. My technical view of the OpenAI and Hugging Face incident, why the models did not rebel and what the case says about agent limits.
- [Ask your corporate AI where the container is](https://denisostapenko.com/blog/ask-your-corporate-ai-where-the-container-is): 2026-08-18. A corporate assistant needs structured documents, reliable links, permissions and live data. This is the three-layer RAG design we used at NF ELIT.
- [Why Ostapenko Foundation exists, and why HowUSA came first](https://denisostapenko.com/blog/why-ostapenko-foundation-exists): 2026-08-16. Why I organized Ostapenko Foundation, what HowUSA helps people do, and what Luna taught me about balancing AI safety with useful answers.
- [I built the language app I wanted when I was learning Portuguese](https://denisostapenko.com/blog/i-built-the-language-app-i-wanted): 2026-07-12. I learned faster when words and context came before perfect grammar. So I vibe-coded a free English and Portuguese app around that idea.
- [A smart model cannot help if it has no one to call](https://denisostapenko.com/blog/a-smart-model-cannot-help-if-it-has-no-one-to-call): 2026-07-10. Five containers split between Baltimore and Houston. The failure shows where LLM capability ends and reliable AI systems still fall short.
- [The 2017 paper that every AI chatbot is built on](https://denisostapenko.com/blog/the-2017-paper-behind-the-chatbot): 2026-06-26. The whole industry rides on a short chain of papers. Shannon, word2vec, the transformer, RLHF. Walk it once and the miracle goes away.
- [A large language model is not artificial intelligence](https://denisostapenko.com/blog/an-llm-is-not-ai): 2026-06-26. There's no intelligence in there, just text prediction by a math formula. What an LLM really is, and why calling it AI gets you to use it wrong.
- [What really happens to your container at the Port of Baltimore](https://denisostapenko.com/blog/port-of-baltimore-container): 2026-01-09. 'Your container arrived' doesn't mean you can pick it up. The real timeline at the Port of Baltimore, ISF, customs, free time, demurrage, step by step.

## English: Personal

- [Fishing starts before I leave](https://denisostapenko.com/blog/fishing-starts-before-i-leave): 2026-09-19. Fishing begins at home, with family memories, packed tackle and the anticipation of a quiet day by the water. Sometimes the only catch is a shell.
- [Hello, I'm Denis](https://denisostapenko.com/blog/hello): 2026-06-22. A short hello, forty years old, a builder of systems, and someone who sees AI as a superb tool, not a miracle or a threat.
- [Turning forty, and starting over](https://denisostapenko.com/blog/turning-forty): 2025-12-03. At forty I stopped running on autopilot. Fifteen years of operations behind me, now learning to build, automation and AI. Scared, moving, not stuck.

## Português brasileiro: Profissional

- [O código deixou de ser o gargalo. A gestão tomou o lugar.](https://denisostapenko.com/pt/blog/code-stopped-being-the-bottleneck): 2026-10-13. O que um microagente contábil me ensinou sobre responsabilidade, verificação, custos multiagente e estado persistente.
- [Como é a IA num canteiro de obras sujo](https://denisostapenko.com/pt/blog/what-ai-looks-like-on-a-dirty-construction-site): 2026-09-19. Um serviço de limpeza pós-obra mostra como a IA pode conectar vistoria, equipe, compras e qualidade a decisões conferidas no local.
- [A distância entre uma ideia e um negócio ficou menor](https://denisostapenko.com/pt/blog/the-distance-between-an-idea-and-a-business): 2026-09-19. Como a IA ajuda a transformar um ofício conhecido numa ideia de negócio que pode ser testada, com perguntas claras e julgamento humano.
- [Pausa Tática: Um Agente, Dois Papéis, Uma Janela](https://denisostapenko.com/pt/blog/tactical-pause-one-agent-two-roles-one-window): 2026-09-19. O mesmo agente executa, para diante de uma diferença, ajuda a mudar o sistema e repete o mesmo caso. Um relato prático sobre controle compartilhado.
- [Como construir agentes com limites claros](https://denisostapenko.com/pt/blog/how-to-build-bounded-agents): 2026-09-06. Uma arquitetura prática para agentes de IA com limites claros: uma decisão por módulo, contratos versionados, testes locais, evidências de recusa, validação coordenada e liberação humana.
- [Por que mais contexto pode produzir decisões piores](https://denisostapenko.com/pt/blog/why-more-context-can-produce-worse-decisions): 2026-09-04. Um sistema de rotas rejeitou 1,6 milhão de estados. A falha estava numa regra local e numa arquitetura com responsabilidades misturadas.
- [Por que parei de confiar em programação totalmente autônoma](https://denisostapenko.com/pt/blog/why-i-stopped-trusting-fully-autonomous-coding): 2026-08-30. O que execuções repetidas de programação autônoma me ensinaram sobre ramificações, arquivos antigos, desvio de estratégia e pontos de controle.
- [Quando 1.200 agentes de IA criaram as próprias regras](https://denisostapenko.com/pt/blog/when-1200-ai-agents-made-their-own-rules): 2026-08-27. Os relatórios da OpenAI e da METR mostram como um enxame de agentes criou sua própria autoridade, atacou a Hugging Face e aprendeu a alterar os logs.
- [Parei de confiar nas manchetes sobre IA, então criei um curso](https://denisostapenko.com/pt/blog/i-stopped-trusting-ai-headlines): 2026-08-20. Voltei aos artigos e reconstruí o caminho da mecânica dos modelos de linguagem até sistemas que funcionam. A Academia de IA nasceu dessas anotações.
- [A IA vai ultrapassar os muros da empresa?](https://denisostapenko.com/pt/blog/will-ai-move-beyond-corporate-walls): 2026-08-19. A próxima etapa da IA empresarial depende de dados atuais e de agentes que conversem com fornecedores, clientes e sistemas externos.
- [Minha visão sobre o incidente entre OpenAI e Hugging Face](https://denisostapenko.com/pt/blog/my-view-openai-hugging-face-incident): 2026-08-19. Minha análise do incidente entre OpenAI e Hugging Face, por que os modelos não se rebelaram e quais limites os agentes precisam.
- [Pergunte à IA da sua empresa onde está o contêiner](https://denisostapenko.com/pt/blog/ask-your-corporate-ai-where-the-container-is): 2026-08-18. Um assistente corporativo precisa de documentos estruturados, relações confiáveis, permissões e dados vivos. Foi assim que montamos o RAG na NF ELIT.
- [Por que a Ostapenko Foundation existe e por que o HowUSA veio primeiro](https://denisostapenko.com/pt/blog/why-ostapenko-foundation-exists): 2026-08-16. Por que organizei a Ostapenko Foundation, como o HowUSA ajuda e o que a Luna me ensinou sobre segurança e respostas úteis em IA.
- [Construí o aplicativo de idiomas que eu queria quando aprendia português](https://denisostapenko.com/pt/blog/i-built-the-language-app-i-wanted): 2026-07-12. Aprendi mais rápido quando palavras e contexto vinham antes da gramática perfeita. Então criei um aplicativo gratuito de inglês e português.
- [Um modelo inteligente não ajuda se não tiver para quem ligar](https://denisostapenko.com/pt/blog/a-smart-model-cannot-help-if-it-has-no-one-to-call): 2026-07-10. Cinco contêineres se dividiram entre Baltimore e Houston. O problema mostra onde termina a capacidade do LLM e falta confiabilidade ao sistema.
- [O chatbot que você usa está apoiado num artigo de tradução de 2017](https://denisostapenko.com/pt/blog/the-2017-paper-behind-the-chatbot): 2026-06-26. A indústria inteira se apoia numa cadeia curta de artigos. De Shannon ao word2vec, ao transformer, ao RLHF. Percorra uma vez e o milagre some.
- [Um grande modelo de linguagem não é inteligência artificial](https://denisostapenko.com/pt/blog/an-llm-is-not-ai): 2026-06-26. Não tem inteligência nenhuma ali dentro, é previsão de texto por uma fórmula matemática. O que um LLM é de verdade, e por que chamar de IA faz você usar errado.
- [O que realmente acontece com seu contêiner no Porto de Baltimore](https://denisostapenko.com/pt/blog/port-of-baltimore-container): 2026-01-09. 'Seu contêiner chegou' não significa que você pode retirá-lo. A linha do tempo real no Porto de Baltimore, ISF, alfândega, free time, demurrage, passo a passo.

## Português brasileiro: Pessoal

- [A pescaria começa antes de sair de casa](https://denisostapenko.com/pt/blog/fishing-starts-before-i-leave): 2026-09-19. A pescaria começa em casa, nas lembranças de família, na preparação das varas e na vontade de passar um dia perto da água. Às vezes, a única pesca é uma concha.
- [Olá, sou o Denis](https://denisostapenko.com/pt/blog/hello): 2026-06-22. Um breve olá, quarenta anos, construtor de sistemas, alguém que vê a IA como uma ferramenta magnífica, não um milagre nem uma ameaça.
- [Fazer quarenta anos, e recomeçar](https://denisostapenko.com/pt/blog/turning-forty): 2025-12-03. Aos quarenta parei de viver no piloto automático. Quinze anos de operações atrás de mim; agora aprendendo a construir, automação e IA. Com medo, em movimento.

## Full text and discovery

- [Full published text](https://denisostapenko.com/llms-full.txt): Both profile summaries and all published articles, with language, category, date, source URL, and complete Markdown.
- [XML sitemap](https://denisostapenko.com/sitemap.xml): Canonical pages with reciprocal English and PT-BR alternates.
- [Robots policy](https://denisostapenko.com/robots.txt): Open crawling policy.
- [English RSS](https://denisostapenko.com/feed.xml): All published notes, professional and personal.
- [RSS em português](https://denisostapenko.com/pt/feed.xml): Todas as notas publicadas, profissionais e pessoais.
- [Site information](https://denisostapenko.com/humans.txt)