are there some complete results on the involutions of 2 sphere?
at least I have three involutions:
(let mathbbZ2=1,g,and S2=(x,y,z)inmathbbR3|x2+y2+z2=1)
1.g(x,y,z)=(−x,−y,−z)(antipodal map) with null fixed point set,and orbit space mathbbRP2
actully,for free involution on Sn with nleq3,the orbit space is homeomorphic to real projective space (Livesay 1960)
2.g(x,y,z)=(−x,−y,z) (rotation pi rad around z axis) with fixed point set S0(the north pole and south pole) and orbit space S2.
3.g(x,y,z)=(x,y,−z)(reflection along z=0) with fixed point set S1 (the equator)and orbit space D2
i want to know if there are some other involutions over 2-sphere.
here we take two involutions as equivalent if there are conjugate in the homeomorphism group of S2
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