CoRN.model.fields.Qfield
Example of a field: 〈Q,[+],[*]〉
As we have seen, there is a inverse for the multiplication for non-zeroes. So, Q not only forms a ring, but even a field.Lemma Q_is_CField : is_CField Q_as_CRing Qinv_dep.
Proof.
red in |- ×.
intro.
unfold is_inverse in |- ×.
apply Qinv_is_inv.
Qed.
Definition Q_as_CField := Build_CField _ _ Q_is_CField Qinv_strext.
Canonical Structure Q_as_CField.