What exactly would count as copyright infringement in a replication paper? I have been following the review process of a replication journal 

In particular, it has an open review which can be seen. 

On a particular submission they are having a debate about whether copying equations and their explanation in a paper counts as copyright infringement.

I would like to ask this question here, since the answer seems non-obvious. 

Equations, by themselves, since they are ideas, should be free from copyright infringement. But to have equations, explanations, replica of figures, and discussion, would basically be a copy of the paper, and I imagine that would be copyright infringement. Where exactly can a line be drawn?

Note: There are questions on stack exchange which ask similar questions, but often in context of building up on previous research. Since the point of such a journal is just to replicate, it would seems that the aim is to build a freely available copy of the existing (perhaps paywalled, copyrighted) material, that can be freely accessed, and this is different intent than regular articles.

Also, answers regarding plagiarism aren't much help in this case as the point is to do "explicit plagiarism" with proper attribution.

Crossposted to law.SE
After asking permission to Elsevier (I'm editor in chief for ReScience), they confirmed (in this specific case) that equations can be re-used without asking permission to Elsevier:


  Our Global Rights group has confirmed that these equations are not
  copyrighted;  therefore, you can merely acknowledge the 2012 Journal
  of Theoretical Biology as the source of the equations but do not
  require written permission from Elsevier.