FSRS vs SM2: How Spaced Repetition Algorithms Work

A technical deep dive into the SM2 and FSRS algorithms that power spaced repetition in tools like Anki. Whether you're curious about how your flashcards are scheduled or exploring alternatives to SM2, this video breaks down how these algorithms work, how they compare, and why FSRS is generally considered superior. 00:00 Intro - Why is FSRS so complicated? 03:02 SM2 Algorithm 08:23 FSRS and Forgetting Curves 12:14 DSR and DHP models 16:17 FSRS equations 21:25 Scheduling Simulator 23:59 Optimization and training weights 26:00 Stochastic Shortest Path Algorithm for Optimizing Spaced Repetition Scheduling https://borretti.me/article/implement... https://borretti.me/article/implement... https://expertium.github.io/Algorithm... https://www.desmos.com/calculator/au5... https://open-spaced-repetition.github... https://dl.acm.org/doi/10.1145/353467... My discord server:   / discord