Definition
Plain language
A formal language for describing the rules of a simulated world so AI planners can reason about it.
As stated in the literature
Planning Domain Definition Language — a standard formalism for representing actions, preconditions, and effects in symbolic planning environments, underpinning text-game benchmarks like ALFWorld.
Why it matters: A formal action language is what makes symbolic planners and text-game benchmarks possible to build and reason about.
For example, a PDDL domain might declare that 'pickup(x)' requires the object to be on the table and results in it being held.
Heard on the show
“ALFWorld, ScienceWorld, TextCraft — these are PDDL-style simulators where the system internally knows exactly what objects exist, what rooms exist, what actions are valid.”Episode 052 — An Old Reinforcement Learning Tradeoff Sneaks Back Into LLM Agents