At 04:09 PM 9/28/04 -0400, you wrote: . . . . . . >Professor Conway, on the other hand, defines a trapezoid as a >quadrilateral with "at least" on pair of parallel sides. Using that >definition, the set of parallelograms is clearly a subset of the set >of trapezoids. Thus, using that definition, every rectangle is a >trapezoid, and also a parallelogram (as is the case with the usual >definition). > >A similar problem exists with the definition of the kite. Most >writers say it is a quadrilateral in which AT MOST one diagonal is the >perpendicular bisector of the other. Conway would say that it is a >quadrilateral in which AT LEAST one diagonal is the perpendicular >bisector of the other. So using Conway's definition, every rhombus is >a kite. > >There have been many, many message threads here on this issue. >Logically, there is a great deal to be said for Prof. Conway's >position.
Amen. Most of the other conflicting definitions defy logic.