Commutators of diffeomorphisms, III: a group which is not perfect.
Let be a foliation of the punctured plane . Any non-compact leaf of has two ends, which we call leaf-ends. The set of leaf-ends which converge to the origin has a natural cyclic order. In the case is infinite, we show that the cyclicly ordered set , obtained by identifying neighbors in and filling in the holes according to the Dedeking process, is equivalent to a circle. We show that the set has a natural topology, and it is homeomorphic to with respect to this topology.
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