16. A computer-implemented method comprising: providing a file as a long-query to a decomposition model, wherein the decomposition model: partitions the file into at least three separate parts; identifies a first part of the at least three separate parts as file-specific words; represents a second part of the at least three separate parts as topic-related words; and discards a third part of the at least three separate parts as background words; and storing a representation of the file indexed by a representation of the topic-related words and by a separate representation of the file-specific words.
16. A computer-implemented method comprising: providing a file as a long-query to a decomposition model, wherein the decomposition model: partitions the file into at least three separate parts; identifies a first part of the at least three separate parts as file-specific words; represents a second part of the at least three separate parts as topic-related words; and discards a third part of the at least three separate parts as background words; and storing a representation of the file indexed by a representation of the topic-related words and by a separate representation of the file-specific words. 18. A computer-implemented method as recited in claim 16 , further comprising performing ranking of the representation of the file based at least on the file-specific words.