One reasoning chain can be wrong
If you sample one CoT and trust it, you've staked the answer on a single sample from a probabilistic process. Two cheap improvements: take multiple samples and reconcile (self-consistency), or branch the reasoning into a tree and prune (Tree-of-Thought).
Self-consistency
Generate N reasoning chains at temperature > 0. Take the answer that appears most often. For tasks with a small answer space (math, classification) this is a measurable accuracy boost.
Tree-of-Thought (ToT)
Generate multiple candidates at each reasoning step, score them, prune. More expensive than self-consistency; more flexible because you can backtrack mid-reasoning. Useful for planning, multi-step search, complex agent loops.
Cost reality
Self-consistency at N=5 costs 5x. Tree-of-Thought costs more. Use these only where accuracy gain is worth the cost — usually high-stakes one-shot tasks, not interactive chat.