The problem of knowing what changed after an action, and what stayed the same.
You move one cereal box in the pantry. Nobody checks if the fridge turned into a dragon.
It trips up common-sense reasoning. It also slows robots and Agents in messy places.
KR
The Frame Problem pushes KR to update only changed facts.
Agent
An Agent gets slow if it recalculates everything before each move.
World model
A world model must know what changed and what stayed the same.
NMR
The Frame Problem and NMR both deal with facts that can change.