I am looking for the name of something that may have one.
A finite algebra $\mathcal{A} = (E, \{f_1, f_2, \ldots, f_k\})$ is a non-empty set $E$ together with some functions $f_i$ from $E^{r_i} \to E$ where $r_i$ is a fixed integer (arity).
An $n$-term is a term on $n$ variables $x_1, \ldots, x_n$ over a finite algebra $\mathcal A$. A term is defined as usual by induction:
- Any element of $E$ and the variables $x_1,\ldots, x_n$ are terms
- If $t_1, \ldots, t_{r_i}$ are terms, then $f_i(t_1,\ldots, t_{r_i})$ is also a term.
An $n$-term $t$ computes a function $[t]\colon E^n \to E$ in an obvious way.
Terminology question: How do we call finite algebras such that for every function $f\colon E^n\to E$, there exists a term $t$ such that $[t] = f$?
Famous example: $$(\{0, 1\}, \{\land, \lor, \lnot\})$$
Famous co-example: $$(\{0, 1\}, \{\land, \lor\})$$