Frechet Borel Ideals with Borel orthogonal

Francisco Guevara, Carlos Uzcategui

We study Borel ideals $I$ on $\mathbb{N}$ with the Fréchet property such its orthogonal $I^{\perp }$ is also Borel (where $A\in I^{\perp }$ iff $A\cap B$ is finite for all $B\in I$ and $…