Definition:Monomorphism (Abstract Algebra)

Definition
A homomorphism which is an injection is descibed as monic, or called a monomorphism.

Group Monomorphism
If both $\left({G, \circ}\right)$ and $\left({H, *}\right)$ are groups, then a monomorphism $\phi: \left({G, \circ}\right) \to \left({H, *}\right)$ is called a group monomorphism.

R-Algebraic Structure Monomorphism
Let $\left({S, \ast_1, \ast_2, \ldots, \ast_n, \circ}\right)_R$ and $\left({T, \odot_1, \odot_2, \ldots, \odot_n, \otimes}\right)_R$ be $R$-algebraic structures.

Then $\phi: S \to T$ is an $R$-Algebraic Structure monomorphism iff:


 * $(1): \quad \phi$ is an injection
 * $(2): \quad \forall k: k \in \left[{1 .. n}\right]: \forall x, y \in S: \phi \left({x \ast_k y}\right) = \phi \left({x}\right) \odot_k \phi \left({y}\right)$
 * $(3): \quad \forall x \in S: \forall \lambda \in R: \phi \left({\lambda \circ x}\right) = \lambda \otimes \phi \left({x}\right)$.

This definition continues to apply when $S$ and $T$ are modules, and also when they are vector spaces.

Monomorphism on an Ordered Structure
A (structure) monomorphism from an ordered structure $\left({S, \circ, \preceq}\right)$ to another $\left({T, *, \preccurlyeq}\right)$ is a mapping $\phi: S \to T$ that is both:


 * A monomorphism, i.e. an injective homomorphism, from the structure $\left({S, \circ}\right)$ to the structure $\left({T, *}\right)$


 * An order monomorphism from the poset $\left({S, \preceq}\right)$ to the poset $\left({T, \preccurlyeq}\right)$.

Category Theory
In a category $\mathcal C$, a monomorphism is a morphism $\alpha \in \operatorname{mor}\mathcal C$ such that $\alpha\beta = \alpha\gamma$ implies $\beta = \gamma$ for all morphisms $\beta,\gamma \in \operatorname{mor}\mathcal C$ for which the composition is defined.

Linguistic Note
The word monomorphism comes from the Greek morphe (μορφή) meaning form or structure, with the prefix mono- meaning single.

Thus monomorphism means single (similar) structure.

Group definition

 * : $\S 7.1$
 * : Chapter $\text{II}$
 * : $\S 47 \ \text{(a)}$

R-Algebraic Structure definition

 * : $\S 28$

Ordered Structure definition

 * : $\S 15$