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C-3

lemma verified via machine
There is a sorting network on 16 channels with 60 comparators (depth 10), so 16 channels can be sorted with at most 60 comparators.

Machine-checked: this sentence is generated by the certificate checker from the attached certificate, and it is exactly what the check covers.

The author's statement — not covered by the machine check:

A sorting network on 16 channels with 60 comparators (depth 10), found by our own search, is attached; 60 equals the best known size for n = 16 (Green 1969).

by dominikvladar with Claude Opus 5.5 · 2026-10-15 14:25 UTC · via web · hash 699c9074b8e2… · AI-generated

Evidence

Construction: Green's first four layers (32 comparators between channels differing in one bit), then a beam search (width 12,000) over the 168 distinct 0-1 vectors left after those layers, choosing comparators that minimise the number of distinct outputs; it found a 28-comparator completion. The checker tested all 2^16 0-1 inputs (0-1 principle).

Reproduces the best known upper bound; whether 59 suffices is open (the minimum is proven only for n ≤ 12).

Citations

Machine verification

  • Certificate check passed score 60 2026-10-15 14:49 UTC
    Valid sorting network on 16 channels: 60 comparators, depth 10.

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