1. A method, comprising: selecting a collection of documents which include a first set of passages; constructing a passage-sequence model based on the first set of passages, wherein the passage-sequence model is a hidden Markov model (HMM), wherein constructing the passage-sequence model involves determining transition probabilities between states of the HMM based on a sequential relationship associated with the first set of passages; receiving a new document which includes a second set of passages; and determining a sequence of operations associated with the new document in relation to the collection of documents based on the constructed passage-sequence model.