Endnote 3 — E.T.A. built as a cardioid

Explains that the Enfield Tennis Academy's four main buildings are curved so that, seen from above, the whole campus forms a valentine, its "Valentine-heart aspect" (p. 983) completed by the dent of the back parking lots. The heart-shaped topology was the work of Avril's late friend, the closed-curve-mapping virtuoso A.Y. "Vector-Field" Rickey of Brandeis, remembered by Hal and Mario for a vest-removal parlor trick that Pemulis later debunked.