15. The non-transitory computer-readable medium of claim 10 , further comprising instructions which, when executed by one or more processors, cause the one or more processors to perform steps comprising: determining whether a size of the first set of one or more sub-sentences exceeds a maximum threshold; in response to determining that the size of the first set of one or more sub-sentences exceeds the maximum threshold, performing the following: determining a second set of one or more nodes to remove from the tree; based on said determining, removing said second set of one or more nodes of the plurality of nodes from the tree; after said removing, reconstructing, from the remaining nodes of the plurality of nodes, a second set of one or more sub-sentences of said one or more sentences, wherein the second set of one or more sub-sentences are shorter in length than said first set of one or more sentences.
16. The non-transitory computer-readable medium of claim 15 , further comprising which, when executed by one or more processors, cause the one or more processors to perform steps comprising: determining that a size of the second set of one or more sub-sentences is less than a minimum threshold; in response to determining that the size of the second set of one or more sub-sentences is less than the minimum threshold, determining whether the second set of one or more sub-sentences contains a named entity; if said second set of one or more sub-sentences contains a recognized named entity, returning the second set of one or more sub-sentences as a title; if said second set of one or more sub-sentences does not contain a recognized named entity, returning said first set of one or more sub-sentences as a title.