12. The non-transitory computer-readable media of claim 11 , where the one or more instructions to cause the processing logic to assign the freshness score to the first document include: one or more instructions to determine a first number of documents in the first set of second documents; one or more instructions to determine a second number of documents in the second set of second documents; one or more instructions to assign a first freshness score to the first document when a ratio of the first number to the second number is larger than a particular value; and one or more instructions to assign a second freshness score to the first document when the ratio of the first number to the second number is smaller than the particular value, where the first freshness score is lower than the second freshness score.
11. The non-transitory computer-readable media of claim 10 , where the one or more instructions to cause the processing logic to determine the times at which the respective links to the first document existed include: one or more instructions to identify a first set of second documents, of the set of second documents, where the link to the first document, for each second document in the first set of second documents, was created after a particular time; and one or more instructions to identify a second set of second documents, of the set of second documents, where the link to the first document, for each second document in the second set of second documents, was created before the particular time.