# Definition:Agreement/Mappings

## Definition

Let:

$(1): \quad f_1: S_1 \to T_1$ be a mapping from $S_1$ to $T_1$
$(2): \quad f_2: S_2 \to T_2$ be a mapping from $S_2$ to $T_2$
$(3): \quad X \subseteq S_1 \cap S_2$

Let:

$\forall s \in X: \map {f_1} s = \map {f_2} s$

Then the mappings $f_1$ and $f_2$ are said to agree on or be in agreement on $X$.