Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2023/ib/paper-2/1e/solution

For
the parity condition is preserved by componentwise addition, negation, and multiplication, and is the identity. Thus is a ring.
It is not an integral domain, since and are nonzero elements of whose product is zero. It is also not a product of two nontrivial rings. Indeed, an idempotent in has each coordinate in , and the parity condition leaves only and . The proved equivalence then excludes a nontrivial product decomposition.

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