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C_81: mark Klyve's upper bound as conditional on GRH - #147

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C_81: mark Klyve's upper bound as conditional on GRH#147
Chessing234 wants to merge 3 commits into
teorth:mainfrom
Chessing234:brun-conditional-bound

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What the page says today

The upper-bound table for $C_{81}$ lists

Bound Reference Comments
2.175398 [K2007]
2.288513 [PT2018]

with both comment cells empty, while the README carries $2.288513$. A reader
comparing the two concludes the README is stale by one row.

It is not. The two bounds are not comparable: [PT2018, §1] states

An excellent exposition of their proof is given in a thesis by Klyve [8] who
also shows that under the assumption of the Generalised Riemann Hypothesis we
have $B < 2.1754$.

and the same paper's abstract gives its own $1.840503 < B < 2.288513$ as
unconditional. So the README is right and the page was missing the one fact
that makes it right.

Changes

Three commits, all on constants/81a.md; no bound values are changed and the
README needs no edit.

  1. Mark the [K2007] row as conditional on GRH and the [PT2018] row as
    unconditional, and explain in "Additional comments" why the README shows the
    larger number.
  2. Add the first upper bound, $B < 2.347$ (Crandall–Pomerance), which the table
    was missing — [PT2018, §1]: "The first upper bound appears to be given by
    Crandall and Pomerance [5], who showed that $B < 2.347$". The 13% improvement
    claimed in that paper's abstract is measured against it. Rows stay in
    chronological order, per CONTRIBUTING.
  3. Say what the lower-bound rows are: partial sums, which is what makes them
    bounds at all, and which distinguishes them from the extrapolated
    $B \approx 1.902$ that is far more widely quoted and is not a bound.

One thing I could not fix

Both Nicely references 404:

https://faculty.lynchburg.edu/~nicely/twins/twins.html    -> 404
https://faculty.lynchburg.edu/~nicely/twins/t2_0001.html  -> 404

He died in 2019 and the Lynchburg pages are gone. trnicely.net still resolves
but is now an unrelated commercial site, so it is not a substitute — I checked
before proposing it. archive.org was returning 502/503 while I was working, so I
did not want to paste a snapshot URL I had not actually opened. The dead state is
noted inline instead, so the next reader does not repeat the search; happy to
swap in a Wayback link if you would rather have one.

The table showed 2.175398 [K2007] above 2.288513 [PT2018] with no
comments, so the page reads as if the best known upper bound were
2.175398 while the README carries 2.288513.  The two are not comparable:
[PT2018, section 1] records Klyve's as "under the assumption of the
Generalised Riemann Hypothesis we have B < 2.1754", and its own result
1.840503 < B < 2.288513 as unconditional.

Both rows now say which they are, and the discrepancy with the README is
explained in the comments section rather than left to be rediscovered.
The bound tables are histories, so the Crandall--Pomerance bound
B < 2.347 belongs in it: [PT2018, section 1] says "The first upper bound
appears to be given by Crandall and Pomerance [5], who showed that
B < 2.347", and the 13% improvement claimed in that paper's abstract is
measured against it.
The lower-bound rows carried no comments, so nothing distinguished the
partial sums recorded here from the extrapolated B ~ 1.902 that is much
more widely quoted and is not a bound.

Both Nicely references 404 as of 17 August 2026 (the author died in 2019
and his Lynchburg pages are gone).  trnicely.net resolves but is now an
unrelated site, so it is not a replacement; noted inline so the next
reader does not repeat the search.
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