Let $C$ be the category of associative commutative rings with 1 and let $F:C\to C$ be a functor which commutes with the forgetful functor to abelian groups (i.e. $F$ is a functorial way to define another multiplication on every associative commutative ring with 1). Is it true that $F$ is the identity functor?
Functorial multiplication on commutative rings
Alexander Braverman
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