TITLE: Would you resubmit a research paper after it has been superseded by another as yet unpublished paper?
QUESTION [25 upvotes]: Hope that the following soft question is still appropriate on MathOverflow. I was wondering if there is any communal protocol or etiquette with regard to the resubmission of a research paper after it has been superseded by another as yet unpublished paper.
Here's the situation in detail. Suppose that a paper of yours, call it paper A, regarding the existence of some mathematical object foobar has been rejected by some journal X. Before you received the news of rejection of paper A by journal X, you obtained bounds on the complexity of foobar and submitted these complexity estimates as paper B to journal Y. Given that paper B is still pending the refereeing process, would you resubmit paper A to another journal X'? Is it unethical to do so?
Of course, one question is what is the worth of paper A, given that it has been superseded by paper B. One possible factor to take into consideration is that paper B is substantially longer than paper A (in my case paper B about 40 pp. and paper A is about 20 pp.). There may be readers interested in the existence argument of paper A without bothering about the complexity estimates in paper B.

REPLY [12 votes]: Yes, you should resubmit. Research is a journey, and having both papers published creates a record which can help others who are tracing the steps of your journey.

REPLY [6 votes]: There is reasonable chance that these papers will be refereed by the same person. Unless both papers are a pleasure to read, you might be unleashing a justified fury of someone who had to do the same hard (and unpaid) job twice. 
On the other hand, I think that the good way to deal with this is to make sure that the overlap of A and B is minimal, and publish A as a preprint (arXiV springs to mind as the right place; I would say, publish B as a preprint, too). In case it's too late, and B contains most of A, I would expect the situation in the 1st paragraph, which would result in both A and B being tainted in editor's views.