Re: [math-fun] cyclic quadrilaterals

On Mon, 27 Oct 2003, Dan Hoey wrote:

Are all such patterns known? Say, given a mapping of a hypergraph to the plane, where vertices are mapped to points, and the images of the vertices of each hyperedge are cocircular, can we tell what other subsets of vertices are forced to map to cocircular points?

I don't know, but I do know some interesting theorems in this line. For example, if all but one of the quadrilaterals AaBb,AaCc,AaDd,BbCc,BbDd,CcDd are cyclic, then so is that last one. JHC