Join-semilattices with two-dimensional congruence amalgamation
Friedrich Wehrung · Colloquium Mathematicum · 2002
We say that a $\langle\vee,0\rangle$-semilattice $S$ is conditionally co-Brouwerian if (1) for all nonempty subsets $X$ and $Y$ of $S$ such that $X\leq Y$ (i.e. $x\leq y$ for all $\langle{x,y}\rangle\in X\times Y$), there exists $z\in S$ such that