From reading the literature of the 1970s heyday of locally convex spaces, it seems that it was an important open question whether there is an infra-Pták (i.e. $B\_r$-complete) space that is not Pták (i.e. $B$-complete). Is this still open?



Infra-Pták space that is not Pták
Valdivia constructed counterexamples in his paper [Br-Complete Spaces which are not B-Complete](https://eudml.org/doc/173399).


