---
title: facts
framework: gameplaykit
role: symbol
role_heading: Instance Property
path: gameplaykit/gkrulesystem/facts
---

# facts

The list of facts claimed by the rule system.

## Declaration

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

## Discussion

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 methods listed in Drawing Conclusions from Facts to examine the grade of a fact or of a combination of facts.

## See Also

### Asserting and Retracting Facts

- [assertFact(_:)](gameplaykit/gkrulesystem/assertfact(_:).md)
- [assertFact(_:grade:)](gameplaykit/gkrulesystem/assertfact(_:grade:).md)
- [retractFact(_:)](gameplaykit/gkrulesystem/retractfact(_:).md)
- [retractFact(_:grade:)](gameplaykit/gkrulesystem/retractfact(_:grade:).md)