$x \mapsto x$, for composition of functions
Terms
| Term | This example | Why |
|---|---|---|
| idempotent | ✓ | $x \mapsto x$ is idempotent, because composing it with itself gives itself. |
| identity element | ✓ | $x \mapsto x$ is the identity element for composition, because composing every function with it gives that function. |
| constant function | ✗ |