wallis-sieve.md
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Wallis sieve
- 2026-09-06 [Proved] The solid Wallis sieve, which drops the centre cube of every surviving cube cut into
(2k+1)^3at levelk, keeps the limit volumeprod_{n odd >= 3} (1 - n^(-3)) = pi^(3/2) / (8 |Gamma(7/4 - i sqrt(3)/4)|^2) = 0.948815486, by the Weierstrass product for1/Gammaafterm^3 - 1 = (m - 1)(m - w)(m - w^2)turns thek-th factor intok (k + (1 - w)/2)(k + (1 - w^2)/2) / (k + 1/2)^3with the three shifts summing to3/2; the plane sieve's limit area is Wallis'spi/4. Witness:mrlynum::sieve::solid_limit, evaluated by the log series to one ulp of0.9488154857196796, checked against the truncated product to1e-14and against the ratio formcosh(pi sqrt(3)/2) / (3 pi)over the even product. - 2026-09-06 [Proved] The Wallis sieve is a mixed-radix schedule word: letter
kis the side-(2k+1)tile with its centre cell removed, the word is their Kronecker fold, and the word's fill is the product of the letters' fills exactly, so any odd schedule in any dimension is a sieve with area the product of its letters' survival ratios. Witness:mrlynum::sieve::ratio, the raster count against the product at levels 1 to 3 in both schedules. - 2026-09-06 [Proved] A schedule of distinct odd letters buys area and a constant one buys a dimension: with strictly increasing odd sides
sum s_k^(-dim)converges, the limit area is positive and the odd word's fill exponentdim + log(ratio_level) / log(side_level)walks up todim(1.972027at plane level 4), while the constant side-sword's stands atlog(s^dim - 1) / log sforever (log 8 / log 3 = 1.892789for the carpet); a schedule that merely varies,3, 5, 3, 5, ..., loses its area and holdslog 192 / log 15 = 1.941432. Witness:mrlynum::sieve::exponent. - 2026-09-06 [Verified] The plane sieve's truncated product reads
0.785398262at two million factors againstpi/4 = 0.785398163, the identity being Wallis's. Witness:mrlynum::sieve::ratio, the test that pins its nine-digit rounding.