Commentary for Kiddushin 119:5

This baraita seems to imply that when one says “Behold this is your divorce from today and after” it is doubtful whether it is a stipulation “from today if I die” in which case she is divorced or a retraction (and means she is divorced only after his death) in which case she is not divorced. To remedy the situation she must have halitzah (in case she is not divorced) but can’t do yibbum (in case she was divorced). This accords well with Rav. And Shmuel could say that this baraita holds like the Rabbis whereas he holds like Rabbi according to whom the divorce is valid for he holds that it is a stipulation.
But according to R. Yohanan who holds that these statements imply “partial” application, this statement should not work at all for there can be no “partial” divorce. There is a rule that the divorce must completely sever the ties between husband and wife. If so, she should be able to have yibbum for she is a widow not a divorcee.