Mechanisms are provided for evaluating a temporal relevance of a portion of content to a cognitive operation request. A cognitive operation request is received that comprises a portion of input text and the input text is analyzed, by a temporal relevance evaluation engine, to identify a temporal focus of the input text. A corpus of content is processed based on the input portion of text to generate candidate results each of which are processed to identify at least one contextual temporal focus associated with the candidate result. The at least one contextual temporal focus is compared with the temporal focus of the input text and a measure of temporal relevance of the candidate result is generated based on results of the comparison. The cognitive operation is performed based on the measure of temporal relevance.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A method, in a data processing system comprising at least one processor and a memory, the memory comprising instructions which are executed by the at least one processor to specifically configure the at least one processor to implement a cognitive system comprising a temporal relevance evaluation engine for evaluating a temporal relevance of a portion of content to a cognitive operation request, the method comprising: receiving, by the cognitive system, a cognitive operation request comprising a portion of input text; analyzing, by the temporal relevance evaluation engine, the input text to identify a temporal focus of the input text; processing, by the temporal relevance evaluation engine, a corpus of content based on the input portion of text to generate candidate results; processing, by the temporal relevance evaluation engine, each candidate result, to identify at least one contextual temporal focus associated with the candidate result; comparing, by the temporal relevance evaluation engine, the at least one contextual temporal focus with the temporal focus of the input text; generating, by the temporal relevance evaluation engine, a measure of temporal relevance of the candidate result based on results of the comparison; and performing, by the cognitive system, the cognitive operation based on the measure of temporal relevance. 2. The method of claim 1, wherein the input text is a natural language question that has at least one term corresponding to a temporal focus of the natural language question, and wherein the candidate results are candidate answers to the natural language question generated from documents of the corpus. 3. The method of claim 1, wherein the input text comprises at least one search term of a search query, and wherein the at least one search term comprises a term corresponding to a temporal focus of the search query, and wherein the candidate results are candidate search results of the search query generated from documents of the corpus. 4. The method of claim 1, further comprising analyzing the documents of the corpus, wherein analyzing the documents of the corpus comprises, for each document: determining a document relevance datetime of the document based on at least one of metadata or content of the document, wherein the document relevance datetime applies to all content of the document; and associating, with each definite temporal expression in the content of the document, a datetime with the definite temporal expression, and wherein the at least one contextual temporal focus of a candidate result generated based on a definite temporal expression in the content of the document is identified based on at least one of the document relevance datetime or the datetime of the definite temporal expression. 5. The method of claim 4, wherein analyzing the documents of the corpus further comprises, for each document: associating with each token in the content of the document, a datetime based on a document relevance datetime associated with the document and a datetime associated with a definite temporal expression that is closest to the token in the document, and wherein the at least one contextual temporal focus of the candidate result generated based on the definite temporal expression in the content of the document is identified based on the datetime of tokens in the candidate result. 6. The method of claim 5, wherein the at least one contextual temporal focus of the candidate result is identified based on the datetime of tokens in the candidate result by combining datetimes of the tokens in the candidate result according to a predetermined relationship. 7. The method of claim 6, wherein the predetermined relationship is one of a union of datetimes of tokens in the candidate result or a minimally overlapping datetime evaluation. 8. The method of claim 4, wherein determining a document relevance datetime of the document comprises determining the document relevance datetime in accordance with an established prioritization of a plurality of types of relevance datetimes. 9. The method of claim 4, wherein the analyzing of the documents is done as part of an ingestion operation for ingesting the corpus prior to receipt of the cognitive operation request. 10. The method of claim 1, wherein analyzing the input text to identify a temporal focus of the input text comprises determining a current datetime and normalizing definite temporal expressions in the input text relative to the current datetime. 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 cognitive operation request comprising a portion of input text; analyze the input text to identify a temporal focus of the input text; process a corpus of content based on the input portion of text to generate candidate results; process each candidate result, to identify at least one contextual temporal focus associated with the candidate result; compare the at least one contextual temporal focus with the temporal focus of the input text; generate a measure of temporal relevance of the candidate result based on results of the comparison; and perform the cognitive operation based on the measure of temporal relevance. 12. The computer program product of claim 11, wherein the input text is a natural language question that has at least one term corresponding to a temporal focus of the natural language question, and wherein the candidate results are candidate answers to the natural language question generated from documents of the corpus. 13. The computer program product of claim 11, wherein the input text comprises at least one search term of a search query, and wherein the at least one search term comprises a term corresponding to a temporal focus of the search query, and wherein the candidate results are candidate search results of the search query generated from documents of the corpus. 14. The computer program product of claim 11, wherein the computer readable program further causes the computing device to analyze the documents of the corpus, wherein analyzing the documents of the corpus comprises, for each document: determining a document relevance datetime of the document based on at least one of metadata or content of the document, wherein the document relevance datetime applies to all content of the document; and associating, with each definite temporal expression in content of the document, a datetime with the definite temporal expression, and wherein the at least one contextual temporal focus of a candidate result generated based on a definite temporal expression in the content of the document is identified based on at least one of the document relevance datetime or the datetime of the definite temporal expression. 15. The computer program product of claim 14, wherein analyzing the documents of the corpus further comprises, for each document: associating with each token in the content of the document, a datetime based on a document relevance datetime associated with the document and a datetime associated with a definite temporal expression that is closest to the token in the document, and wherein the at least one contextual temporal focus of the candidate result generated based on the definite temporal expression in the content of the document is identified based on the datetime of tokens in the candidate result. 16. The computer program product of claim 15, wherein the at least one contextual temporal focus of the candidate result is identified based on the datetime of tokens in the candidate result by combining datetimes of the tokens in the candidate result according to a predetermined relationship, wherein the predetermined relationship is one of a union of datetimes of tokens in the candidate result or a minimally overlapping datetime evaluation. 17. The computer program product of claim 14, wherein determining a document relevance datetime of the document comprises determining the document relevance datetime in accordance with an established prioritization of a plurality of types of relevance datetimes. 18. The computer program product of claim 14, wherein the analyzing of the documents is done as part of an ingestion operation for ingesting the corpus prior to receipt of the cognitive operation request. 19. The computer program product of claim 11, wherein the computer readable program causes the computing device to analyze the input text to identify a temporal focus of the input text at least by determining a current datetime and normalizing definite temporal expressions in the input text relative to the current datetime. 20. 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 cognitive operation request comprising a portion of input text; analyze the input text to identify a temporal focus of the input text; process a corpus of content based on the input portion of text to generate candidate results; process each candidate result, to identify at least one contextual temporal focus associated with the candidate result; compare the at least one contextual temporal focus with the temporal focus of the input text; generate a measure of temporal relevance of the candidate result based on results of the comparison; and perform the cognitive operation based on the measure of temporal relevance.