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4 essays across 2 questions.

  1. Transformer Math · Part 1 The transformer is a learned probability model A joint probability over sequences is impossible to store. The chain rule turns it into one function you can learn. Sep 2026 8 min read
  2. Reinforcement learning · Part 1 From Bellman to Rainbow RL isn’t solvable — it can only be estimated. This essay collects everything you need to know about reinforcement learning. Sep 2026 27 min read
  3. Transformer Math · Part 3 The residual stream is the model Every explanation of transformers spends itself on attention, which is a third of the model. The other two thirds are MLPs — and the thing they all write into is where the model actually lives. Jul 2026 3 min read
  4. Transformer Math · Part 2 Attention is a lookup table you learn Before any of the scale questions, the mechanism. Attention is not “the model focusing” — it is a differentiable dictionary, and once you see it that way every design choice downstream stops being arbitrary. Jul 2026 3 min read