A Series of Unfortunate Events the plot of "The Grim Grotto", the eleventh book. The Baudelaire orphans are named after Charles Baudelaire; Violet's name also comes from the T.S. Eliot's poem "The Waste Land", specifically its verses concerning the "violet hour," and Sunny and Klaus take their first names from Claus and Sunny von Bülow, while Mr. Poe is a reference to Edgar Allan Poe (his sons are named Edgar and Albert). In the seventh installment, "The Vile Village," Count Olaf's disguise, Detective Dupin, is an allusion to C. Auguste Dupin, a fictional detective created by Edgar Allan Poe. Isadora and Duncan Quagmire are named
Dupin cyclide of Dupin cyclides is invariant under the larger group of all Lie sphere transformations; any two Dupin cyclides are Lie-equivalent. They form (in some sense) the simplest class of Lie-invariant surfaces after the spheres, and are therefore particularly significant in Lie sphere geometry. The definition also means that a Dupin cyclide is the envelope of the one-parameter family of spheres tangent to three given mutually tangent spheres. It follows that it is tangent to infinitely many Soddy's hexlet configurations of spheres. A further special property of a cyclide is: An elliptic cyclide can be represented parametrically by the following formulas