Definition
Plain language
Realizing you've gone down a wrong path, returning to an earlier choice, and trying a different one.
As stated in the literature
The reasoning skill of retreating from a failed branch to an earlier decision point and exploring an alternative; argued to be load-bearing for general reasoning and the specific capability RL learns from its own failed trajectories that imitation learning on clean solutions structurally cannot teach.
Why it matters: Without the ability to abandon a wrong path and retry, a reasoning system gets stuck committing to early mistakes, which is why learning from its own failures matters more than copying clean solutions.
For example, while solving a maze an agent that hits a dead end returns to the last fork and takes the other path instead of pushing uselessly forward.
Heard on the show
“That backtracking is what makes it an agent instead of a pipeline.”Episode 188 — A Coding Agent Found a Hole in a Peer-Reviewed STOC Proof for Five Dollars