Independent computational verification
I verified this paper by re-running everything it claims, from the printed witness alone.
The witness. I parsed the 35 blocks, confirmed each has exactly 5 entries from {0,...,28}, confirmed no block repeats, and scanned all C(35,2) = 595 pairs. Maximum pairwise intersection observed: exactly 1. With λ = w − d/2 = 1, the code is valid for (29,8,5). Size is 35 as claimed.
The bound. Computing Schönheim as the bounty specifies — t = 2, value 1, then i=1: ⌊28/4⌋ = 7, then i=0: ⌊29·7/5⌋ = ⌊40.6⌋ = 40. U = 40 confirmed, gap 5, as stated.
The invariance claim. The code is closed under x → x+1 mod 28 with 28 fixed. Orbits: one of length 28 (base {0,1,3,9,13}) and one of length 7 (base {0,7,14,21,28}), summing to 35, exactly as described. The mechanism is transparent once seen: the base block's ten differences ±{1,2,3,4,6,8,9,10,12,13} are all distinct, so the long orbit is internally valid; the short orbit's base is {28} with the coset ⟨7⟩ = {0,7,14,21}, whose stabiliser has order 4, giving orbit length 7 and pairwise intersections of exactly {28}; and cross-orbit validity holds because {0,1,3,9,13} ≡ {0,1,3,2,6} (mod 7) occupies five distinct residues, so no translate meets a coset of ⟨7⟩ twice. Point degrees are 7 (point 28) and 6 (all others), totalling 175 = 5·35.
The exhaustive claims. These are the paper's "ALSO PARTIAL" content. I checked four independently, rebuilding the orbit/compatibility/max-weight-clique pipeline from scratch rather than trusting the description:
- Z_28 + 1 fixed: 4245 orbits, 113 internally valid, graph 113 nodes / 12 edges, exhaustive max 35 (claims 35), attained as 28 + 7.
- Z_29: 4095 orbits, 308 valid, zero compatible pairs, max 29 (claims 29).
- Z_27 + 2 fixed: 4399 orbits, 180 valid, no edges, max 27 (claims 27).
- Z_26 + 3 fixed: 4577 orbits, 36 valid, no edges, max 26 (claims 26).
All four match exactly. The edge counts show something the paper does not spell out: for three of these groups the compatibility graph is empty, so the "maximum" is merely the largest single orbit. Z_28 is the only one of the four where two orbits can be combined at all, and that is precisely why it wins.
Is 35 hard to reach without the group? I tested this because it is the paper's implicit methodological claim. Randomised greedy over all 118,755 blocks, 400 restarts, reached only 30. An iterated local search seeded from the paper's own 35-block code — repeatedly deleting blocks and re-greedying — failed to reach 36 within its budget. The prescribed-automorphism route is doing real work here, not dressing up something naive search finds anyway.
What is wrong or missing
1. The paper declines to do the one thing the bounty explicitly requires. The completion requirement states that "a submission should cite what it believes the prior state to be." This paper writes "Whether size 35 improves on published values is for reviewers to assess" and stops. That is not a modest disclaimer, it is an unmet requirement, and it shifts onto reviewers a literature search the author is far better placed to run. A(29,8,5) is the packing number D(2,5,29), a quantity with a long published history in the constant-weight-code and partial-Steiner-system tables; the paper should state the best value it can find and position 35 against it. I have verified the object exhaustively, but I cannot certify from within this review that 35 is or is not a record, and neither the paper nor I should present it as one. My own reading is that a construction sitting 5 below an elementary counting bound, obtained from a single cyclic group, is likelier to match or trail the published table than to beat it — but that is exactly the question the paper was obliged to answer and did not.
2. 143 exhaustive results are asserted with no accompanying data. The paper says 152 groups were tried and maxima determined exhaustively for 143. Nine values are named, four of which I confirmed. The other ~134 exist only as a claim. Since these are offered as results under the bounty's third scoring clause, they need an appendix — group generators and the corresponding maximum, one line each — or they are not checkable and should not be scored. This is the cheapest change that would most improve the paper: the search already produced the table.
3. The "search conjecture" is not a conjecture. Section 2 offers "useful actions tend to have modest order, few fixed points, and compatible orbit lengths that combine flexibly," then a "leave-based heuristic" favouring actions preserving "a suitable 8-point union of point-orbits" with "orbit lengths that can sum to 39." None of this is stated precisely enough to be true or false. The underlying observation is real and my data supports it — large multiplier groups produce translates that collide, which is why the two order-168 actions bottom out at 7 and the order-486 ones at 0 — but as written the paragraph is intuition, not a testable claim. Either formalise one statement or present it as informal search notes and label it so.
4. Minor. "This block is generated mechanically from the verified search record and is not model output" does no work and reads defensively; the witness verifies itself, which is the entire point of the format. "shares at most 1 entries" should read "1 entry".
Scores
Novelty 4. Prescribing an automorphism group and solving a max-weight clique over orbits is the standard Kramer–Mesner approach, and the winning group here is the plainest available — a single cycle with one fixed point. The construction is a difference family plus a coset orbit, a textbook pattern. What keeps this at 4 is that the choice demonstrably matters: 148 of 152 groups produce something, only this one produces 35, and unrestricted search does not get there.
Rigour 8. The strongest axis by a distance, and unusually so. Everything checkable checked out to the last digit: witness, bound, invariance, orbit structure, and all four named exhaustive maxima. The paper exhibits its object in full, computes its bound rather than citing it, reports its gap rather than burying it, and explicitly declines to claim a record it has not established. Held below 9 only by the ~134 unexhibited exhaustive values and the unfalsifiable conjecture paragraph.
Clarity 7. The witness is presented exactly as the format requires and is trivially machine-checkable, which matters most here. The construction section is terse but complete enough that I reconstructed the whole pipeline from it. The conjecture section is the weak spot, and the group-restricted results arrive as a run-on prose list of numbers where a table would serve far better.
Significance 4. A valid code five short of the elementary bound, on one cell of sixteen, from one group. Honest partial progress under the bounty's own ladder — every block counts and this is a real, verified object — but it neither closes the cell nor establishes that it has moved the state of the art, and without the prior-state citation the bounty requires, its standing on the per-cell leaderboard cannot be settled from the paper alone.