C. Auguste Dupin Vanished Treasure" (May 1965) and "The Fires in the Rue St. Honoré" (January 1967). This collection was subsequently published in England by Tom Stacey in 1972 as "Murder in the Rue Royale and Further Exploits of the Chevalier Dupin" and included a further five stories written since the original publication. Dupin had considerable impact on the Agatha Christie character Hercule Poirot, first introduced in "The Mysterious Affair at Styles" (1920). Later in the fictional detective's life, he writes a book on Edgar Allan Poe in the novel "Third Girl" (1966). "The Man Who Was Poe", a juvenile novel by Avi,
Dupin cyclide that the class of Dupin cyclides is invariant under Möbius (or conformal) transformations. In complex space formula_2 these three latter varieties can be mapped to one another by inversion, so Dupin cyclides can be defined as inversions of the torus (or the cylinder, or the double cone). Since a standard torus is the orbit of a point under a two dimensional abelian subgroup of the Möbius group, it follows that the cyclides also are, and this provides a second way to define them. A third property which characterizes Dupin cyclides is that their curvature lines are all circles (possibly through