Ring Homomorphism Preserves Zero
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Theorem
Let $\phi: \struct {R_1, +_1, \circ_1} \to \struct {R_2, +_2, \circ_2}$ be a ring homomorphism.
Let:
Then:
- $\map \phi {0_{R_1} } = 0_{R_2}$
Proof
By definition, if $\struct {R_1, +_1, \circ_1}$ and $\struct {R_2, +_2, \circ_2}$ are rings then $\struct {R_1, +_1}$ and $\struct {R_2, +_2}$ are groups.
Again by definition:
- the zero of $\struct {R_1, +_1, \circ_1}$ is the identity of $\struct {R_1, +_1}$
- the zero of $\struct {R_2, +_2, \circ_2}$ is the identity of $\struct {R_2, +_2}$.
The result follows from Group Homomorphism Preserves Identity.
$\blacksquare$
Sources
- 1964: Iain T. Adamson: Introduction to Field Theory ... (previous) ... (next): Chapter $\text {I}$: Elementary Definitions: $\S 3$. Homomorphisms
- 1969: C.R.J. Clapham: Introduction to Abstract Algebra ... (previous) ... (next): Chapter $5$: Rings: $\S 24$. Homomorphisms: Theorem $44 \ \text{(i)}$
- 1970: B. Hartley and T.O. Hawkes: Rings, Modules and Linear Algebra ... (previous) ... (next): $\S 2.2$: Homomorphisms: Definition $2.4$
- 1978: Thomas A. Whitelaw: An Introduction to Abstract Algebra ... (previous) ... (next): $\S 57.1$ Ring homomorphisms: $\text{(i)}$