Tests the validity of the observation, namely whether is it inside the
range of the input universe in each dimension.
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Parameters
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fis - structure describing the fuzzy inference system.
The partitions are normalized.
obs - structure describing the observation corresponding to the
normalized partitions.
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Returned values
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Valid - true - the observation fits the input universe
- false - in one or more dimensions the observation is outside the
range of the input variable
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Remarks
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