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Involutions of knots that fix unknotting tunnels. (English) Zbl 1147.57004

Summary: Let \(K\) be a knot that has an unknotting tunnel \(\tau\). We prove that \(K\) admits a strong involution that fixes \(\tau\) pointwise if and only if \(K\) is a two-bridge knot and \(\tau\) its upper or lower tunnel.

MSC:

57M25 Knots and links in the \(3\)-sphere (MSC2010)
57M60 Group actions on manifolds and cell complexes in low dimensions

References:

[1] DOI: 10.1007/BF01444492 · Zbl 0830.57009 · doi:10.1007/BF01444492
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[4] DOI: 10.1007/BF02566211 · Zbl 0469.57005 · doi:10.1007/BF02566211
[5] DOI: 10.1016/S0079-8169(08)61637-2 · doi:10.1016/S0079-8169(08)61637-2
[6] DOI: 10.1007/BF01446565 · Zbl 0697.57002 · doi:10.1007/BF01446565
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