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\}$