Fact invalidation / temporal memory

What is fact invalidation, and what is temporal memory?

Fact invalidation is what a memory system does when something it stored stops being true. Temporal memory is the broader property of tracking not just what is true but when it was true. Both exist because facts about people expire: roles change, tools get replaced, decisions get reversed. A system without either treats a two-year-old statement as current and confidently tells you something wrong. The stronger approach is not to delete the outdated version but to mark it superseded, so the system knows both what is current and what used to be — which is what lets it explain how a decision changed.