Den Ducoff is a Lean Notes founder. In addition to being a beginner Lean student, he is also an advisor and curator with respect to the Lean Notes website. ![[Den Small.jpg]] [Send dducoff an email](https://docs.google.com/forms/d/e/1FAIpQLSePHGQBb1hx3ZAGjOoCq0GeCnq3k2BOfTV6niJiYw8tWCjKpA/viewform) --- ## Beginner Lean student - Currently working through - Kevin Buzzard's videos, [Formalising mathematics course 2022](https://www.youtube.com/playlist?list=PLVZep5wTamMmRPvCLO4WVpCwkTi1F6OyF) - Bhavik Mehta's 2025 course, [Formalising Mathematics 2025](https://b-mehta.github.io/formalising-mathematics-notes/). The GitHub site is [here](https://github.com/b-mehta/formalising-mathematics-notes). ## Retired tutor in Algebra, PreCalculus, Calculus - 30 years of tutoring experience - Certified Math Substitute Teacher in the Boulder Valley School District - Math Tutor for advanced subjects at Front Range Community College, Westminster, Colorado - BA in Math with additional graduate work in math and computer science - Teach once ... learn twice --- ![[Den's Mineral King Hike.jpg|526x296]] [A short video of Den's epic hike in the Sierra Nevadas](https://www.youtube.com/watch?v=C9TLVovr14A)