I'm editing a paper and I'm not sure about commas after "Then" as an opener in a new sentence. Here's the context:
"the velocities can be computed as [some math here]. Then, the [other math thing I was just talking about before] can be expressed as [another equation here]."
Should that comma be there? I can see both sides. If the "then" is meant to express "as a direct result of this" the comma adds emphasis and sets it off. If it's just a transition to move to the next thing, then I think the comma shouldn't be there.
Is there a hard and fast rule about this?
Then is technically a conjunctive adverb, so you would use a semi-colon before then and a comma after it. It's a bit old school, though, and you could get away with a comma. I'm seeing it more and more.
My instinct said semicolon/comma combo too. That's what I changed it to. Thanks!