4-slope Kakeya-type sum-difference constant (3c)

4-slope Kakeya-type sum-difference constant

Upper bound, last-listed row

| $2 - \frac{1}{4} = 1.75$ | [KT1999] | |tracked since 2026-07-24 — no movement seen yet

Lower bound, last-listed row

| $1.6747338950414058$ | [L2026] | Entropy construction on a 147-point support, exact rational weights at denominator $10^{320}$. Certified $C_{3c} \geq 1.674733895041405870063135756722213999136383713818148696811828$, with $H(X-Y) = 1.90118266043426947934\ldots$ and $H(X) = H(Y) = H(X+Y) = H(X+2Y) = 1.13521477415805507651\ldots$ (natural logarithm), so no constraint is slack. Improves [MI2026] by $2.06 \times 10^{-11}$. |

value changed 2026-09-26

Cite this row

Bounds Ledger — 4-slope Kakeya-type sum-difference constant (3c)
upper bound: $2 - \frac{1}{4} = 1.75$ (tracked since 2026-07-24 — no movement seen yet)
lower bound: $1.6747338950414058$ (value changed 2026-09-26)
Mirrored from teorth/optimizationproblems@2c1968c. These are the last-listed rows of that constant's bounds table — a listing position, not a statement that this bound is the strongest or most recent. A snapshot at that sha, not a live read.
https://u00dxk2.github.io/bounds-ledger/c/3c.html