Let $(M, *)$ be a magma. $(N, *)$ is a submagma of $(M, *)$, written $N \leq M$, if $(N, *)$ itself is a magma and $N \subseteq M$.
Let $(M, *)$ be a magma. $(N, *)$ is a submagma of $(M, *)$, written $N \leq M$, if $(N, *)$ itself is a magma and $N \subseteq M$.