If, however, we just want to determine if a given state is present
or not, then the answer is: "usually".
What is a hash?
As far as we are concerned a hash is an array of buckets. The index
of the bucket into which a given state goes is determined according to a
deterministic hash function.
A hash function is highly magical and should make sure similar records
have very distinct hash values, and all hash values are generated
in roughly equal frequency.