There's an old problem in 4-manifold theory that, as far as I know, doesn't have a name associated with it and really deserves a name.
Let M be a smooth 4-manifold with boundary. Let S be a smoothly embedded 2-dimensional sphere in partialM. Assume S does not bound a ball in partialM, but S is null-homotopic in M. Does S bound a smooth 3-ball in M? Perhaps you need to replace S by another non-trivial S′ in partialM before you can find a 3-ball in M bounding it?
You could think of this as the co-dimension one analogue to Dehn's lemma for 4-manifolds. Usually when people talk about a Dehn lemma for 4-manifolds they're interested in the co-dimension 2 analogue.
Does this problem / conjecture have a name? If not, do you have a good name for it? Do you know of anywhere in the literature where this issue is investigated?
Off the top of my head the only vaguely related things I know about in the literature is a 1975 paper of Swarup's.
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