A mechanism is provided in a data processing system for exploring knowledge. The mechanism receives a set of known facts. The mechanism traverses paths in an ontology for a domain of knowledge from known facts in the set of known facts to one or more hypotheses. The ontology includes a plurality of entity types and a plurality of relationships between the entity types. The mechanism presents one or more hypotheses to a user.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A method, in a data processing system, for exploring knowledge, the method comprising: receiving, by the data processing system, a set of known facts; traversing, by the data processing system, paths in an ontology for a domain of knowledge from known facts in the set of known facts to one or more hypotheses, wherein the ontology includes a plurality of entity types and a plurality of relationships between the entity types; and presenting, by the data processing system, the one or more hypotheses. 2. The method of claim 1, wherein receiving a set of known facts comprises receiving an input specifying the set of known facts. 3. The method of claim 2, wherein the input asks for an unknown entity, the method further comprising: determining a set of hypotheses based on a semantic type of the unknown entity. 4. The method of claim 1, wherein traversing the paths in the ontology comprises: determining a semantic type of each known fact in the set of known facts; determining a semantic type for the one or more hypotheses; and determining a set of paths in the ontology from the semantic type of each known fact to the semantic type for the one or more hypotheses. 5. The method of claim 4, wherein traversing a given path in the ontology comprises: instantiating a source node of the given path with a known fact in the set of known facts; and instantiating an unknown argument of each relationship in the given path. 6. The method of claim 4, wherein traversing a given path in the ontology comprises: instantiating an end node of the given path with a hypothesis; and instantiating an unknown argument of each relationship in the given path. 7. The method of claim 5, wherein instantiating the unknown argument of each relationship in the given path comprises looking up the relationship in a database or knowledge base. 8. The method of claim 5, wherein instantiating an unknown argument of a given relationship in the given path comprises: submitting a question to a question answering system; and receiving an answer from the question answering system. 9. The method of claim 8, wherein the answer has an associated answer confidence value, the method further comprising determining a hypothesis confidence value for the given path based on the answer confidence value. 10. The method of claim 9, further comprising ranking the one or more hypotheses based on hypothesis confidence value. 11. A computer program product comprising a computer readable storage medium having a computer readable program stored therein, wherein the computer readable program, when executed on a computing device, causes the computing device to: receive a set of known facts; traverse paths in an ontology for a domain of knowledge from known facts in the set of known facts to one or more hypotheses, wherein the ontology includes a plurality of entity types and a plurality of relationships between the entity types; and present the one or more hypotheses. 12. The computer program product of claim 11, wherein traversing the paths in the ontology comprises: determining a semantic type of each known fact in the set of known facts; determining a semantic type for the one or more hypotheses; and determining a set of paths in the ontology from the semantic type of each known fact to the semantic type for the one or more hypotheses. 13. The computer program product of claim 12, wherein traversing a given path in the ontology comprises: instantiating a source node of the given path with a known fact in the set of known facts; and instantiating an unknown argument of each relationship in the given path. 14. The computer program product of claim 13, wherein instantiating the unknown argument of each relationship in the given path comprises looking up the relationship in a database or knowledge base. 15. The computer program product of claim 13, wherein instantiating an unknown argument of a given relationship in the given path comprises: submitting a question to a question answering system; and receiving an answer from the question answering system. 16. An apparatus comprising: a processor; and a memory coupled to the processor, wherein the memory comprises instructions which, when executed by the processor, cause the processor to: receive a set of known facts; traverse paths in an ontology for a domain of knowledge from known facts in the set of known facts to one or more hypotheses, wherein the ontology includes a plurality of entity types and a plurality of relationships between the entity types; and present the one or more hypotheses. 17. The apparatus of claim 16, wherein traversing the paths in the ontology comprises: determining a semantic type of each known fact in the set of known facts; determining a semantic type for the one or more hypotheses; and determining a set of paths in the ontology from the semantic type of each known fact to the semantic type for the one or more hypotheses. 18. The apparatus of claim 17, wherein traversing a given path in the ontology comprises: instantiating a source node of the given path with a known fact in the set of known facts; and instantiating an unknown argument of each relationship in the given path. 19. The apparatus of claim 18, wherein instantiating the unknown argument of each relationship in the given path comprises looking up the relationship in a database or knowledge base. 20. The apparatus of claim 18, wherein instantiating an unknown argument of a given relationship in the given path comprises: submitting a question to a question answering system; and receiving an answer from the question answering system.