斯坦福EE364a课程布置的作业答案，内容为第2章《凸集》3.2 Level sets of conve C, concave, quasiconvex and quasiconcave functions. Some level sets
of a function f are shown below. The curve labeled 1 shows a f(a)=1
2
Could f be convex(concave, quasiconvex, quasiconcave)? Expl
