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# grade(forFact:)

Returns the membership grade of the specified fact.

```
func grade(forFact fact: any NSObjectProtocol) -> Float
```

## Parameters

`fact`

An object representing a truth claimed or rejected by the rule system. For details, see the [`facts`](/documentation/GameplayKit/GKRuleSystem/facts) property.

## Return Value

A value in the range [0.0, 1.0] representing the fact’s membership grade.

## Discussion

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. Use the [`GKRuleSystem`](/documentation/GameplayKit/GKRuleSystem) methods listed in Asserting and Retracting Facts to add or remove facts and set their membership grade—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.

If the specified fact is not in the [`facts`](/documentation/GameplayKit/GKRuleSystem/facts) array, this method returns `0.0`.

## See Also

[`facts`](/documentation/GameplayKit/GKRuleSystem/facts)

The list of facts claimed by the rule system.


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