Determines whether the current set is a proper (strict) subset of a specified collection.
Assembly: System (in System.dll)
If the current set is a proper subset of other, other must have at least one element that the current set does not have.
An empty set is a proper subset of any other collection. Therefore, this method returns true if the current set is empty, unless the other parameter is also an empty set.
This method always returns false if the current set has more or the same number of elements than other.