Putnam 1967 A1. Let u n be the number of symmetric matrices whose elements are all 0 or 1, with exactly one 1 in each row. K is a convex, finite or infinite, region of the plane, whose boundary is a union of a finite number of straight line segments. Find necessary and sufficient conditions on a i and b i for this maximum to be achieved. Show that the midpoints of the other three sides form an equilateral triangle.
R is the reals.
R is the reals. To avoid possible copyright problems, I have changed the wording , but not the substance , of all the problems. Out of print, but in some university libraries.