TITLE: is there a better classification of a desirable algebra?
QUESTION [6 upvotes]: Consider a finite-dimensional, associative algebra presented as follows:
$$\mathcal{A} = e_1 \mathbb{R}\oplus e_2 \mathbb{R} \oplus \cdots \oplus e_n \mathbb{R} $$
with multiplication $*: \mathcal{A} \times \mathcal{A} \rightarrow \mathcal{A}$ defined by linearly extending
$$  \color{red}{ e_i *e_j = C_{ij}^ke_k \qquad \text{no summation over $k$ intended}.} $$
For example, the direct product algebra $e_i*e_j = \delta_{ij}e_i$ fits this condition.
The clarity of the multiplication is partly from a good choice of notation. If I took a different basis then the multiplication could get muddled. For example, $\mathbb{R}^2$ with the commutative direct product algebra is described by $e_1 *e_1=e_1$ and $e_2*e_2=e_2$ and $e_1*e_2=0$. If I instead presented the multiplication by $f_1 = 2e_1+3e_2$ and $f_2=e_1+e_2$ then $f_1*f_1 = 5f_1-6f_2$.
Apparently I could be given an algebra where a proper change of notation would induce the $\color{red}{\text{desired property}}$. For the sake of this question, let us define $\mathcal{A}$ as desirable iff there exists some basis $\{f_1,\dots f_n \}$ for $\mathcal{A}$ such that $f_i *f_j = C_{ij}^kf_k$ where no summation is intended over $k$.

Question: is there a more standard term for a desirable algebra?

Please point me towards a respected reference for your term if at all possible. Thanks is advance for your help!

REPLY [5 votes]: A multiplicative basis of an algebra $A$ is a basis $B\subseteq A$ such that for all $b_1$, $b_2\in B$ we have either $b_1b_2\in B$ or $b_1b_2=0$ —sometimes, this is extended a bit by allowing in the first possibility that $b_1b_2$ be a scalar multiple of an element of $B$. In any case, this is more general than the semigroup algebras that Bill mentions, because I am allowing here the second option.
This is a pretty standard notion that comes up in the study of finite dimensional algebras. There are lots of algebras with multiplicative bases, the path algebra of a quiver being a basic example. Moreover, multiplicative bases show up in very important results.
One example: it is a theorem that finite dimensional algebras of finite representation type have multiplicative bases; this is a very difficult result due to R. Bautista, P. Gabriel, A. Roiter and L. Salmerón. The converse is not true, and there are group algebras, for example of infinite representation type.