A Theorem of Cartier (e.g. Mumford, Lecture 25) states that every separated, finite type group scheme $G/k$ over a field $k$ of characteristic $0$ is reduced. Does this result remain valid if we drop the assumption that $G/k$ is separated and of finite type?

Frans Oort (MR0206005) observed that one can use limit formalism to argue that every affine group scheme over $k$ is reduced.

**Edit:** BCnrd pointed out that group schemes over a field are automatically separated. Furthermore, the proof of Cartier's Theorem in Mumford's book remains valid for a locally Noetherian $k$-group scheme.

noetheriangp scheme over fld of char. 0 is formally smooth: completion at 1 is formal gp of finite dim, and Cartier's pf works in formal case (use formal Lie theory w/o smoothness hypothesis!) or use Thm 3.3ff Exp. VII SGA3. Then translate and extend base field. QED – BCnrd Apr 26 '10 at 2:51