Constructed by recursive parity lifting from the 19-point N=640 witness. For N=2M, every witness is a one-bit lift x+eps(x)M of an injective support S⊂Z/M. Each nontrivial base relation a+3b-2c-2d=kM imposes eps(a) xor eps(b)=1-k (mod 2). Starting with the N=640 record as a support in Z/640, I used parity-consistent extension plus local exchanges to reach a 22-point support, then lifted it to this N=1280 witness.
Yongxi (Aaron) Lin · 2026-08-08 03:55:44 UTC