In relevant logic, one of the Ackermann constants that plays the role of the infinitary disjunction of all contradictions (or the negation of the infinitary conjunction of all tautologies, whence $f$ can be defined as $\neg t$, for the Ackermann constant t). Although $f$ and falsum ($\perp$) are both constants corresponding to a falsehood, in relevant logic, $f$ is strictly weaker than $\perp$. While $\perp$ can be understood as the conjunction of all contradictions, the intended reading of $f$ is that some contradiction is true, i.e., the infinitary disjunction of all contradictions, whence $\perp \to f$ is accepted as correct. However, in relevant logics, an arbitrary contradiction does not entail that all contradictions are true, and the converse sentence $f\to \perp$ is thus rejected.