Is a field a Hopf algebra?

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Is a field a Hopf algebra? I'm not sure but I think that a field is a Hopf algebra.

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When you talk about Hopf algebras you have fixed a ground field $k$ and you are really talking about Hopf $k$-algebras.

Now a Hopf $k$-algebra $H$ comes with a counit $\epsilon:H\to k$ which is a map of $k$-algebras. If $H$ is a field, this counit must be injective and, since it is always surjective, it is an isomorphism.

This tells us that the unique Hopf $k$-algebra which is a field is $k$ itself.