Sentence diagramming is the long division of English. It involves a bewildering array of lines and diagonal branches. It is loathed as an elementary school chore. And it is presumed to be obsolete.

What tools does a grammarian need? A brain helps, and so does a computer, but surely one of our most essential tools is some kind of diagramming system. How can we think about a sentence’s structure, ...

This makes the two ideas equal in the sentence - if you take away one part of it, you are left with a simple sentence again. These are very common when speaking and they are not difficult to ...