# Definition:Backward Shift Operator

## Definition

Let $T = \sequence {z_t}$ be a discrete time series.

The backward shift operator $B$ is defined as:

$\forall t: \map B {z_t} = z_{t - 1}$

## Sources

$1$: Introduction:
$1.2$ Stochastic and Deterministic Dynamic Mathematical Models
$1.2.1$ Stationary and Nonstationary Stochastic Models for Forecasting and Control: Some simple operators