The Argon Book

Argon is a typed knowledge graph, a rule engine, and a bitemporal store, in one language. It models a domain precisely — its concepts, the relations between them, the rules that classify and derive — and runs that model as a database that answers questions and accepts changes. Three commitments separate it from a database with a schema: the classifying vocabulary is declared in the language rather than built in, knowledge is four-valued so a missing or disputed fact has its own answer, and every model’s reasoning cost is a tier the compiler computes and bounds.

The Reference fixes the exact rules — terse, complete, anchored to the Lean mechanization; where it and this book disagree on a rule, the Reference is correct. Argon by Example holds the runnable programs, compiled and run in CI.