Definition:Fiber of Truth

Definition
Let $\Bbb B = \left\{{T, F}\right\}$ be a boolean domain.

Let $f : X \to \Bbb B$ be a boolean-valued function.

The fiber of truth (under $f\,$) is the fiber or preimage of $T$ and can be denoted $ \left[\left|{f}\right|\right]$:


 * $ \left[\left|{f}\right|\right] = \left\{{x \in X: f \left({x}\right) = T}\right\}$

Comment
The phrase fiber of truth (with the same meaning) is occasionally seen in natural language.

In particular:
 * "... to extract the fiber of truth from this tissue of lies ..."

sounds as though it would be used in the context of the courtroom by a lawyer waxing rhetorical.