Understanding Rings: Example of Homomorphism/Isomorphism

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SUMMARY

The discussion centers on providing an example of a ring homomorphism that does not satisfy the additive property. The example given involves the rings R and S both being the integers, denoted as $\Bbb Z$. The function defined is f(k) = k^2, which satisfies the multiplicative property f(ab) = f(a)f(b) for all a, b in R, but fails the additive property f(a+b) ≠ f(a) + f(b) for certain values of a and b. This illustrates a clear distinction between homomorphisms and isomorphisms in ring theory.

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  • Understanding of ring theory concepts, specifically rings and their properties.
  • Familiarity with homomorphisms and isomorphisms in abstract algebra.
  • Basic knowledge of functions and their properties in mathematics.
  • Ability to work with integer operations and polynomial functions.
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  • Study the properties of ring homomorphisms in greater detail.
  • Explore examples of isomorphisms between different algebraic structures.
  • Learn about the implications of additive and multiplicative identities in ring theory.
  • Investigate the role of polynomial functions in defining mappings between rings.
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Mathematics students, particularly those studying abstract algebra, educators teaching ring theory, and researchers exploring algebraic structures.

corkycorey101
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Can you give an example of two rings R and S, and a function f:R⟶S such that f(ab)=f(a)f(b) for all a,b ∈ R, but f(a+b)≠f(a)+f(b) for some a,b ∈ R. I know that it has to do with proving homomorphisms/isomorphisms but am confused how to come up with the actual example.
 
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Let $R = S =\Bbb Z$, the ring of integers, and set:

$f(k) = k^2$.
 
Oh wow, that was easier than I thought. I was way over thinking it. Thank you so much!
 

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