a multiplicative map mapping a commutative ring to a commutative ring preserves identity
1026
Ring homomorphism with $\phi(1_R) \neq1_S$
108742
Proving commutativity of addition for vector spaces
112131
Characterizing all ring homomorphisms $C[0,1]\to\mathbb{R}$.
119702
Showing a bijection between the set of ringhomomorphisms $\mathbb{Z}[i] \to R$ and the set of $x \in R$ for which $x^2+1=0$
149856
Image of ring homomorphism is a subring
87946
Proving that the unities of a ring form a group under multiplication
60760
Ring homomorphism and characteristic
41035
Mapping that proves $\mathbb{Z} \subset \mathbb{Q}$
6385
Minimal counterexamples of the isomorphism problem for integral group rings
52354
Given a idempotent endomorphism, show that $M = \ker(f) \oplus \ker (f-\text{id}_M)$
123044
Commutative matrices are multiples of the identity
50037
Proving that kernels of evaluation maps are generated by the $x_i - a_i$
103924
Kernel of a substitution map
35034
Multiplicative inverses for $Z_n$
27265
Continuously differentiable map from $\mathbb{R}^{m+n}$ to $\mathbb{R}^n$
140865
Rings' second isomorphism theorem
109080
Is the kernel of a map to a finitely presented module finitely generated?