1. A method for testing a sub-ontology for safeness, the sub-ontology comprising one or more elements of a given ontology, the elements comprising one or more individuals, one or more relationships defined between the one or more individuals and one or more pieces of metadata relating to the one or more individuals and the one or more relationships, the method comprising: defining a first subset of the one or more relationships, the first subset comprising all sensitive relationships in the given ontology; defining a second subset of the one or more relationships, the second subset comprising the sub-ontology; and determining whether any relationship in the first subset can be inferred from any relationship in the second subset, given one or more inference rules.