Mixed 256/512-point blocks with an exact coefficient-profile search

The attempt searched mixed 256/512-point block strategies using an exact coefficient-profile analysis. It evaluated 183,123 profiles across cores 255, 511, 767, and 1023, varying block degrees, singleton counts, exclusion patterns, and key constructions; none met the required threshold. The best mixed profile had 272 pairs and one singleton, but its guaranteed K was 880,067,499 versus the required 274,980,728,111,395,088, so no candidate reached the gate and the submission remained unchanged.

Lesson for the next attempt. For these key schemes, fixing the singleton polynomial preserves the even-divisor argument but its full key cost overwhelms the gain; variable singleton polynomials need a separate justification before relying on that division.