In an introductory post on Grimm Machines, I give a narrative to suggest why the following link between a given algorithm S
and Grimm's conjecture should be studied. In this post, I give a summary (as suggested by W.H.Wlodzimierz Holsztynski) as well
as new information and a new technical question.
Edit 2016.08.24 At W.H.'s polite request, I revised the title.
I ran computations for $L$ out to $1.6*10^9$ and found about 100
additional intervals on which $L$ is not injective. I will try
a modified version that combines S and $L$ and report back. It seems
many (maybe all but one?) of the $L$ intervals have a Case I fix, because
there are very few smooth numbers between consecutive primes, and
powers of 2 seem to avoid most of the problematic intervals.
Until another natural divisor map suggests itself to me as being
a good candidate for a Grimm map, I am going with a modified
version which runs S and $L$ and uses S unless $L$ works better.
I have a part of an idea which suggests why S works better. Every
jump of a prime $p$ for a distance $kp$ requires that its target
$n+kp$ have its largest prime factor at most $kp$. Thus small primes
tend to skip over nonsmooth numbers in a fashion where I am trying to
quantify nonsmooth. In any case, $L$ fails to be injective through
multiples of many pairs of consecutive or nearby pairs of smooth numbers,
while $S$ fails to be injective due to short jumps of a prime when
longer jumps might normally be expected. END Edit 2016.08.24.