The mkfile used to build this paper expects two subdirectories holding
different checked-out branches of the MRFy repository at
`git@github.com:ndaniels/MRFy.git`

  - Subdirectory `mrfy` must contain a copy of the branch
    `implicit-cumulative-costs`.

  - Subdirectory `nr-jfp` must contain a copy of the branch `nr-jfp`.

If the mkfile barfs or if not all expected tools are installed, it's
possible that some joy might be obtained by

    mk codes
    pdflatex jfp

The mkfile doesn't run bibtex; for that you're on your own.