[see also: either
Both f and g are obtained by...... [Or: f and g are both obtained]
For both C∞ and analytic categories,......
Here C behaves covariantly with respect to maps of both X and G.
We now apply (3) to both sides of (6).
Both conditions <Both these conditions/Both the conditions> are restrictions only on...... [ Note: the after both]
Then C lies on no segment both of whose endpoints lie in K.
Two consecutive elements do not belong both to A or both to B.
Both its sides are convex. [Or: Its sides are both convex.]
Here B and C are nonnegative numbers, not both 0.
Choose points x in M and y in N, both close to z, such that......
We show how this method works in two cases. In both, C is......