# On a tower of strongly normal extensions

Where I could see the following statement?

Let $K\subset L\subset M$ be a tower of the strongly normal extensions of differential fields. If $M$ is weakly normal over $K$, then $M$ is strongly normal over $K$.

• Thank you for counterexample professor Pillay. I have read the above statement many years ago and do not remember where. So, apparently, I missed some important condition of context. Maybe $K$ must be finitely generated and finite transcendence degree over the constants. – user75594 Jul 1 '15 at 17:31