Definition:Backward Path (Class Theory)

Definition
Let $A$ be a class under a total ordering $\preccurlyeq$.

Let $S = \sequence n_{n \mathop \in \N}$ be a sequence in $A$ (either finite or infinite) such that:
 * $\forall i \in \N: x_i \in S \implies x_{i + 1} \prec x_i$

Then $S$ is referred to as a backward path of $\preccurlyeq$ (in $A$).