The dimension test for balanced holomorphic vertex operator algebras at central charges 32 and 40
Abstract
Ampagouni, Mason and Mertens single out a class of holomorphic vertex operator algebras V=ℂ1oplus V₁oplus V₂oplus… that they call balanced, for which the Virasoro vectors of V and of the subalgebra generated by V₁ coincide when the central charge is 32 or 40 and V₁ ≠ 0, and they enumerate the 449 semisimple balanced root systems at c=32 and the 1277 at c=40. Three computational tests then try to rule each of them out. The cheapest is the dimension test: the integer m=dim V₂-dim L_(widehat(g))(k,0)₂ must be a non-negative integer combination of the top-level dimensions of the conformal-weight-two modules of widehat(g). At c=32 exactly two root systems defeated even this test for want of resources, A_(1,64)³A_(4,160) and A_(5,64); we decide both. The test excludes A_(5,64), by a size obstruction (m=147519 while every conformal-weight-two module has top-level dimension at least 3 845 961, a minimum we determine exactly), and it does not exclude A_(1,64)³A_(4,160), where m=147094=6288 · 23+10 · 247 is certified on the three A_(1,64) factors alone. At c=40 the source ran no test in its body, and its ancillary table records a result for 154 of the 1277 rows. We machine-check the census #BRS(40,0)=1277 (and find #BRS(10,0)=22 where the source prints 42), we show that the dimension test excludes 93 of the 1123 rows with no recorded result, and we show that one row the ancillary table marks as excluded by the dimension test, A_(5,48)B_(2,24), is in fact not excluded by it. The c=40 exclusions are stated about modules rather than about a computed list, through a completeness theorem for a pruned enumeration of the conformal-weight-two modules. A non-exclusion is not an existence statement, and an exclusion is an exclusion by this test only. All numbered statements are machine-checked in Lean 4; a displayed closed form for m in the source is also corrected.
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Claim ledger
Stated results
BR1known data2026-09-03
The value of m = dim V₂ − dim L_𝔤̂(k,0)₂ at the three cells treated here, and its check against the two realised lattice theories E_(8,1)⁴ and D_(32,1), where m = 0
BR2correction2026-09-03
Erratum: the displayed closed form m = dim V₁ + 139504 − dim Sym²𝔤 in arXiv:2602.12312v3 §5.1 is wrong; the coefficient of dim V₁ should be 247
BR3candidate2026-09-03
The dimension test excludes the root system A_(5,64) at c = 32 (arXiv:2602.12312v3 Appendix A row 26), one of the two cells the source states it could not run
BR4candidate2026-09-03
The dimension test does not exclude the root system A_(1,64)³ A_(4,160) at c = 32 (arXiv:2602.12312v3 Appendix A row 2), the other cell the source states it could not run
BR5known data2026-09-03
Control: the dimension test excludes A_(6,14) (arXiv:2602.12312v3 Appendix A row 72), reproducing the source's own X (dim) label through the same machinery and by the source's own gcd(D) ∤ m criterion
BR6measurement2026-09-03
Audit of arXiv:2602.12312v3 Appendix A: 443 of the 447 decidable cells reproduced; the printed table carries 122 X (dim) rows against the prose's '121'; four cells named where the label is not reproduced
This ledger entry is reported in prose and is not bound to a Lean theorem.BR7candidate2026-09-03
The smallest conformal-weight-2 module of A₅¹ at level 64 has top-level dimension exactly 3 845 961, at λ = ω₁ + 4ω₄ + 11ω₅ and its dual; there are 80 such highest weights and every one has level at most 19
BR8routine2026-09-03
Negative controls: the bound of BR7 is sharp, the exclusion of BR3 is about the target and not about D (3 845 961 is representable), 23 ∤ 147094, 23p + 247q = 100 is unsolvable, the A₁ weights 21 and 23 do not have conformal weight 2, and casA/dimA reproduce the adjoint and fundamental dimensions
BR9known data2026-09-03
The census of semisimple balanced root systems is kernel-bound: # BRS(40,0) = 1277 (and 449 at c = 32, 3294 at c = 48, and every value the source prints for c ≤ 9, 16, 24), together with the finiteness theorem dim 𝔤 ≤ c(1+h^∨) that makes the search finite
BR10correction2026-09-03
Erratum: arXiv:2602.12312v3 Table tab:numBRS prints # BRS(10,0) = 42; the correct value is 22
BR11candidate2026-09-03
The dimension test excludes A_(6,35) at c = 40 (row 137 of the ancillary Tablesc40all.pdf, which records no result for it); the smallest conformal-weight-2 module of A₆¹ at level 35 has top-level dimension exactly 194 480, and there are 56 such weights, all of level ≤ 13
BR12candidate2026-09-03
The dimension test excludes A_(3,1)⁴ G_(2,1)¹⁰ at c = 40 (row 1221, no result recorded) by a genuine coin-problem obstruction: neither of the two criteria the source states decides it
BR13candidate2026-09-03
The dimension test excludes A_(40,1) at c = 40 (row 1276, the largest single-factor row of the table, d₁ = 1680, no result recorded): A₄₀¹ at level 1 has no module of conformal weight 2 at all
BR14measurement2026-09-03
The c = 40 dimension test run on all 1 277 rows: 94 of the 1 123 rows the source's ancillary table leaves blank are excluded (62 by gcd(D) ∤ m, 10 by a size obstruction, 22 by a coin-problem failure); and an audit of the ancillary's own labels — 94 of its 118 X (d) rows reproduced, the 24 exceptions named, 36 of 36 X (J) consistent
This ledger entry is reported in prose and is not bound to a Lean theorem.BR15routine2026-09-03
Negative controls for c = 40: the bound of BR11 is sharp and attained twice, 194 480 is representable, the A₆ weight condition and the level both bite, A₄₀ has 41 level-one modules but none of conformal weight 2, neither part of the row-1221 certificate alone divides m, 90 515 is representable, and gcd(D) = 1 with m below the Frobenius number
BR16known data2026-09-03
The c = 40 value of m, checked against the two realised lattice rows E_(8,1)⁵ (row 1274) and D_(40,1) (row 1277), both of which give m = 0; and the level-one correction shown to be mandatory — without it D_(40,1) gets m = −3 409 560
BR17candidate2026-09-03
The dimension test excludes 6 balanced root systems of central charge 40 with d₁ = 41 — ancillary rows 2, 3, 4, 5, 7, 8 of Tablesc40all.pdf, for none of which the source records any result (3 by gcd(D ∩ [1,m]) ∤ m, 2 by a size obstruction, 1 by a coin-problem failure)
BR18candidate2026-09-03
The dimension test excludes 9 balanced root systems of central charge 40 with d₁ = 42 — ancillary rows 26, 27, 29, 30, 31, 32, 33, 40, 45 of Tablesc40all.pdf, for none of which the source records any result (0 by gcd(D ∩ [1,m]) ∤ m, 5 by a size obstruction, 4 by a coin-problem failure)
BR19candidate2026-09-03
The dimension test excludes 4 balanced root systems of central charge 40 with d₁ = 43 and 44 — ancillary rows 57, 62, 68, 71 of Tablesc40all.pdf, for none of which the source records any result (2 by gcd(D ∩ [1,m]) ∤ m, 0 by a size obstruction, 2 by a coin-problem failure)
BR20candidate2026-09-03
The dimension test excludes 8 balanced root systems of central charge 40 with d₁ = 48 — ancillary rows 138, 139, 140, 148, 155, 158, 163, 164 of Tablesc40all.pdf, for none of which the source records any result (7 by gcd(D ∩ [1,m]) ∤ m, 0 by a size obstruction, 1 by a coin-problem failure)
BR21candidate2026-09-03
The dimension test excludes 3 balanced root systems of central charge 40 with d₁ = 60 and 105 — ancillary rows 274, 280, 924 of Tablesc40all.pdf, for none of which the source records any result (0 by gcd(D ∩ [1,m]) ∤ m, 1 by a size obstruction, 2 by a coin-problem failure)
BR22candidate2026-09-03
The dimension test excludes 10 balanced root systems of central charge 40 with d₁ = 120 (1 of 4) — ancillary rows 950, 951, 954, 955, 956, 958, 962, 963, 970, 971 of Tablesc40all.pdf, for none of which the source records any result (7 by gcd(D ∩ [1,m]) ∤ m, 0 by a size obstruction, 3 by a coin-problem failure)
BR23candidate2026-09-03
The dimension test excludes 10 balanced root systems of central charge 40 with d₁ = 120 (2 of 4) — ancillary rows 975, 976, 979, 981, 982, 984, 985, 988, 989, 990 of Tablesc40all.pdf, for none of which the source records any result (9 by gcd(D ∩ [1,m]) ∤ m, 0 by a size obstruction, 1 by a coin-problem failure)
BR24candidate2026-09-03
The dimension test excludes 10 balanced root systems of central charge 40 with d₁ = 120 (3 of 4) — ancillary rows 1003, 1006, 1018, 1019, 1025, 1026, 1028, 1039, 1040, 1066 of Tablesc40all.pdf, for none of which the source records any result (6 by gcd(D ∩ [1,m]) ∤ m, 0 by a size obstruction, 4 by a coin-problem failure)
BR25candidate2026-09-03
The dimension test excludes 12 balanced root systems of central charge 40 with d₁ = 120 (4 of 4) — ancillary rows 1067, 1101, 1104, 1109, 1110, 1113, 1114, 1115, 1117, 1118, 1119, 1120 of Tablesc40all.pdf, for none of which the source records any result (12 by gcd(D ∩ [1,m]) ∤ m, 0 by a size obstruction, 0 by a coin-problem failure)
BR26candidate2026-09-03
The dimension test excludes 7 balanced root systems of central charge 40 with d₁ = 160 and 180 — ancillary rows 1138, 1142, 1143, 1144, 1184, 1191, 1192 of Tablesc40all.pdf, for none of which the source records any result (5 by gcd(D ∩ [1,m]) ∤ m, 0 by a size obstruction, 2 by a coin-problem failure)
BR27candidate2026-09-03
The dimension test excludes 11 balanced root systems of central charge 40 with d₁ = 200 and 240 — ancillary rows 1207, 1208, 1209, 1210, 1211, 1214, 1215, 1218, 1222, 1223, 1241 of Tablesc40all.pdf, for none of which the source records any result (10 by gcd(D ∩ [1,m]) ∤ m, 0 by a size obstruction, 1 by a coin-problem failure)
BR28correction2026-09-03
Correction: the ancillary Tablesc40all.pdf of arXiv:2602.12312v3 records X (d) for row 93, A_(5,48) B_(2,24) (c = 40, d₁ = 45), but the dimension test does not exclude it — m = 41 860 = 88·385 + 4·1995, and the two conformal-weight-2 modules of dimensions 385 and 1995 are exhibited
BR29routine2026-09-03
Negative controls for the 90 c = 40 exclusions: the size obstruction is about size and not emptiness (B_(7,8) has exactly three conformal-weight-2 modules, of dimensions 230 945, 271 700, 388 960, all above m = 67 030; B_(3,100)² has one of dimension 419 881 above m = 40 507), a too-small claim is refuted, the coin obstruction is one unit wide at row 274 (m − 1 = 48 489 is representable, m = 48 490 is not), the level-one correction moves m by 1127 at row 1223, and the conformal-weight condition bites
BR30known data2026-09-03
The c = 40 dimension test as a kernel statement about modules: RepByModules and the completeness theorem mem_wt2DimsSmall, with a dimension prune, two interchangeable complete per-factor enumerations and deduplication — the engine that turns each of the 94 exclusions into three data (factor list, common denominator, m)
Provenance
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- Machina Mathematica
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- Korea Superintelligence Labs
- Source context
- A *holomorphic* vertex operator algebra V = ℂ𝟏 ⊕ V₁ ⊕ V₂ ⊕ … of central charge c is one whose only irreducible module is itself. For c = 24 the possible weight-one Lie algebras V₁ are Schellekens's list of 71. Ampagouni–Mason–Mertens (arXiv:2602.12312v3, math.QA, 20 Mar 2026) carry the analogous programme to c = 32 for the class they call balanced — V is balanced when the Virasoro vector of V and of the subVOA generated by V₁ coincide — and enumerate 449 semisimple balanced root systems. Three computational tests then try to rule each of them out. The cheapest is th
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- 2026-09-07 03:53 UTC
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