Commutative diagram for morphism.
<a href="//commons.wikimedia.org/w/index.php?title=User:Cepheus&amp;action=edit&amp;redlink=1" class="new" title="User:Cepheus (page does not exist)">User:Cepheus</a>
Own work, based on <a href="https://en.wikipedia.org/wiki/Image:MorphismComposition-01.png" class="extiw" title="en:Image:MorphismComposition-01.png">en:Image:MorphismComposition-01.png</a>