[R] Superimposing y-variables in Lattice formulas

[Stavros Macrakis]

Thank you for the pointer to your paper "Getting Started with Lattice
Graphics" -- it looks very useful.

I think we're talking past each other on the question of the semantics
of formula operators, and it's probably not productive to continue.  I
would guess that the underlying issue is that we come from different
communities, and so have different background assumptions.  Perhaps
it's the old MIT vs New Jersey story
(http://www.jwz.org/doc/worse-is-better.html) -- after all, S/R does
come out of the Bell Labs community, and I was in the MIT Lisp
community many decades ago....

            -s