PART 1: source text of Written on the Wall
   ok, 16 checks so far
PART 2: 843 is not among the conjectures the book records as tested
   ok, 19 checks so far
PART 3: implementations, calibrated against independently known facts
   calibration passed, 129 checks so far
PART 4: the counterexample, C240 = GP(2,2) = leapfrog(GP(2,0))
   C240: alpha <= 108, conjecture needs >= 112, margin -4.  508 checks so far
PART 5: minimality -- 843 has NO counterexample among the small fullerenes
   per-order profile (n : isomers : certified bound on n/2-alpha):
      n=20       1 isomers   deficiency <= 2
      n=24       1 isomers   deficiency <= 3
      n=26       1 isomers   deficiency <= 3
      n=28       2 isomers   deficiency <= 3
      n=30       3 isomers   deficiency <= 3
      n=32       6 isomers   deficiency <= 3
      n=34       6 isomers   deficiency <= 3
      n=36      15 isomers   deficiency <= 4
      n=38      17 isomers   deficiency <= 4
      n=40      40 isomers   deficiency <= 4
      n=42      45 isomers   deficiency <= 5
      n=44      89 isomers   deficiency <= 5
      n=46     116 isomers   deficiency <= 5
      n=48     199 isomers   deficiency <= 5
      n=50     271 isomers   deficiency <= 5
      n=52     437 isomers   deficiency <= 6
      n=54     580 isomers   deficiency <= 6
      n=56     924 isomers   deficiency <= 6
      n=58    1205 isomers   deficiency <= 6
      n=60    1812 isomers   deficiency <= 6
   exhaustive to n = 60: 5770 isomers, deficiency always <= 6, 843 never fails
   theorem-based floor: any counterexample has n >= 136.  23692 checks so far
PART 6: an infinite family, with margin tending to minus infinity
   GP(1,1): n=60    alpha <= 24    n/2-8 = 22    margin +2
   GP(2,2): n=240   alpha <= 108   n/2-8 = 112   margin -4
   GP(3,3): n=540   alpha <= 252   n/2-8 = 262   margin -10
   GP(4,4): n=960   alpha <= 456   n/2-8 = 472   margin -16
   GP(5,5): n=1500  alpha <= 720   n/2-8 = 742   margin -22
   margin 8 - 6k -> -infinity.  24164 checks so far
PART 7: honesty, provenance and ledger self-check

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CONJECTURE 843 OF 'WRITTEN ON THE WALL' IS FALSE.
Counterexample: C240 = GP(2,2), the leapfrog of C80.
V(C240) partitions into twelve 5-cycles and twelve 15-cycles,
hence alpha <= 12*2 + 12*7 = 108 = n/2 - 12 < 112 = n/2 - 8.
Margin -4.  The family GP(k,k) gives margin 8 - 6k -> -infinity.
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all 24376 checks passed