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cobordism
Which homology 3-spheres bound homology 4-balls? ★★★★
Author(s): Ancient/folklore
Problem Is there a complete and computable set of invariants that can determine which (rational) homology
-spheres bound (rational) homology
-balls?
![$ 3 $](/files/tex/4aaf85facb6534fd470edd32dbdb4e28f6218190.png)
![$ 4 $](/files/tex/1f1498726bb4b7754ca36de46c0ccdd09136d115.png)
Keywords: cobordism; homology ball; homology sphere
Slice-ribbon problem ★★★★
Author(s): Fox
Conjecture Given a knot in
which is slice, is it a ribbon knot?
![$ S^3 $](/files/tex/02a9a17122cd1be0450f9ddf93c53e3feb250aad.png)
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