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# facts

The list of facts claimed by the rule system.

```
var facts: [Any] { get }
```

## Discussion

A fact is any object representing a truth claimed by the rule system. You can use any type of object to represent the facts in your system: simple data types like strings and numbers typically suffice, but you can also use custom objects from your game’s data model.

Each fact has a membership grade ranging from zero to 1.0, representing variable levels of truth, strength, or confidence for use in fuzzy logic. Asserting a fact increases its grade, adding it to the array if not present; retracting a set reduces its grade, removing it from the array if its grade drops to zero. Use the [`GKRuleSystem`](/documentation/GameplayKit/GKRuleSystem) methods listed in Drawing Conclusions from Facts to examine the grade of a fact or of a combination of facts.

---

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