Definition:Labeled Tree for Propositional Logic/Ancestor WFF
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Definition
Let $\struct {T, \mathbf H, \Phi}$ be a labeled tree for propositional logic.
A WFF that is attached to an ancestor node of a node $t$ is called an ancestor WFF of $t$.
So a hypothesis WFF is an ancestor WFF of every node of $T$.
Also known as
An ancestor WFF of $t$ is also referred as just an ancestor of $t$.
When using the term ancestor in this way, take care to avoid confusion with the concept of ancestor node.
Sources
- 1996: H. Jerome Keisler and Joel Robbin: Mathematical Logic and Computability ... (previous) ... (next): $\S 1.7$: Tableaus