Definition:Labeled Tree for Propositional Logic/Attached

Definition
Let $\left({T, \mathbf H, \Phi}\right)$ be a labeled tree for propositional logic. Let $t$ be a non-root node of $T$.

Let $\mathbf A$ be a WFF such that $\mathbf A = \Phi \left({t}\right)$.

Then $\mathbf A$ is attached to $t$.

All the WFFs in the hypothesis set $\mathbf H$ are considered to be attached to the root node.

Also known as
The statement $\mathbf A$ is attached to $t$ can also be seen as:


 * $\mathbf A$ occurs at $t$
 * $\mathbf A$ is $t$.