Composition

• $M_{ab}$ is a Morphism from $A$ to $B$
• $M_{bc}$ is a Morphism from $B$ to $C$
• $M_{bc}$ $\circ$ $M_{ab}$ is the Composition of the above functions that maps $A$ to $C$
  • It is equivalent to applying $M_{ab}$, then applying $M_{bc}$
  • It can be thought of as: $M_{bc}$ follows $M_{ab}$
  • Composition is Associative $\to (f\circ g)\circ h=f\circ (g\circ h)$