Approximate modularity: Kalton's constant is not smaller than 3

Michal Gnacik, Marcin Guzik, Tomasz Kania

Kalton and Roberts [Trans. Amer. Math. Soc., 278 (1983), 803--816] proved that there exists a universal constant $K⩽44.5$ such that for every set algebra $\mathcal{F}$ and…