Tuesday March 21, 2000
- Wrap up Convex Hull topic: lower bound for convex
hulls. Textbook, Ch. 3.6, page 96.
Duality applet from Jim Henle's page. Textbook, Ch. 6.5, page
- Duality properties: dual of dual gets you back to where you
started. Preserves incidences (point on line, line through point;
line through two points, point of intersection of two
lines). [parabola duality] Preserves above/below properties.
- A dictionary of dual terms:
Arrangements of lines vs. configurations of points.
Upper and lower envelopes vs. convex hulls. Solving a problem for
lines by reducing it (via duality) to a problem for points (upper
envelope; intersection of half-planes).
- Reading: Textbook, Ch.6.
Last modified March 21, 2000.