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 # Check

 Last update: 17.07.2025 

The Check library provides a set of operators to build oracles for test harnesses, which are divided into several categories.

- **Properties**: The properties are evaluated during several cycles. The triggering condition, if any, is evaluated only once unless the operator is restarted.
- **Interval checks**: The operators check an input signal is within or out of some range.

Operator NameDescription[Always](check__always.md)Returns true while the input property has never been false.[AlwaysAfterCond](check__alwaysaftercond.md)Returns true while the input property has never been false after a condition becomes true.[AlwaysAfterN](check__alwaysaftern.md)Returns true while the input property has never been false after a given number of cycles.[AtLeastCond](check__atleastcond.md)Returns true if the input property has always been true before the first occurrence of the condition.[AtLeastN](check__atleastn.md)Returns true if the input property has been true for the first given number of cycles.[AtMostCond](check__atmostcond.md)Returns true if the input property is always false after the first occurrence of the condition.[AtMostN](check__atmostn.md)Returns true if the input property is always false after the first given number of cycles.[BeforeCond](check__beforecond.md)Returns true if the input property is true at least once before the condition is true.[BeforeN](check__beforen.md)Returns true if the input property is true at least once before the first given number of cycles.[BetweenCond](check__betweencond.md)Returns false if p has not been true after the start condition is true and before the end condition is true.[BetweenN](check__betweenn.md)Returns false if p has not been true within the next n cycles once c becomes true.[Bounds](check__bounds.md)Checks if the input signal is within an interval.[ConfirmN](check__confirmn.md)Returns true if the input property has been true for a given number of cycles.[Cycles](check__cycles.md)Returns true after a given number of cycles.[Gap](check__gap.md)Checks if the input signal is out of an interval.[Gradient](check__gradient.md)Checks if the absolute value of the input signal gradient is less than a maximum value.[IgnoreCond](check__ignorecond.md)Returns the input property as soon as the input condition turns to true, otherwise true.[IgnoreN](check__ignoren.md)Returns the input property after a given number of cycles, otherwise true.[Implies](check__implies.md)Returns the logical expression: not(P) or Q.[ImpliesCond](check__impliescond.md)Returns the value of q until c is true starting when p is true, otherwise true.[ImpliesN](check__impliesn.md)Returns the value of q during n cycles starting when p is true, otherwise true.[LowerBound](check__lowerbound.md)Checks if the input signal is greater than the lower bound.[Never](check__never.md)Returns true while the input property has never been true.[Once](check__once.md)Returns true once the input property has been true.[UpperBound](check__upperbound.md)Checks if the input signal is less than the upper bound.**Parent topic:**[Libraries](../../libraries/libraries.md)