Uniqueness of orientation preserving ๐๐ฟ involutions of 3-space
Kyung Whan Kwun, Jeffrey L. Tollefson ยท Bulletin of the American Mathematical Society ยท 1973
PROOF. We indicate how to modify the proof of Lemma 2 of [1] to produce the desired invariant 3-cell D. We may assume that F is not contained in U. Let 2 be the set of all in M {x} that bound 3-cell neighborhoods of x in U and are in /z-general position moduloF (in the sense of [l]).The lemma follows from the proof of Lemma 2 of [1] if the phrase 2-spheres not bounding is replaced by PL in M โ {x} bounding 3-cell neighborhoods of x in 17. In order to prove Theorem 2, consider a sequence of invariant 3-cells