Or, put in examples: which of the following is grammatically correct?


  Either you or your sister is going to have to do the chores.





  Either you or your sister are going to have to do the chores.


The second option comes off as really strange; am I right to say that the first is grammatically correct because "is" directly follows "your sister" as opposed to "you"?


Question: Identifying sequential patterns
Answer: You can map the data into a feature space where sequence is important, along with both statistics calculated over sliding windows &amp; cumulative statistics, and use that in a decision tree.

A decision tree could handle both sequences and non-sequential data.  This may substantially reduce your data complexity.