🎯Core Definition
CoT (Chain-of-Thought) decomposes hard problems into explicit intermediate reasoning steps at inference time; RL-fortified reasoning (RLVR+GRPO) instead bakes long-chain reasoning into the parameters at training time — CoT is the decoding-time behavior those models exhibit, and the two complement each other.
💡Use Cases
multi-step reasoning (math, logic, code); in RL, CoT is the policy's generation form and RL optimizes its distribution and test-time scaling.
⚡Key Problems Solved
single-step big-O reasoning is error-prone and unlocalizable; CoT decomposition plus outcome/process rewards mitigate error propagation and credit assignment. See the LLM module: full content in the LLM module's cot card (guide reasoning-and-cot).