We again drew a picture of the (possible) structure of NP (showing P, NPC, and the problems in between), and we reviewed the meaning of NP-Completeness.
We proved the NP-Completeness of STICK DRAWING. An instance of this problem is a collection of sticks of different lengths (described as a list of numbers) and a drawing showing a picture in the plane composed of line segments (described by a list of pairs of ordered pairs of integers). The question is whether or not you can draw the given drawing using the given sticks. Sticks can be placed end-to-end but can not otherwise overlap. You are required to use up all the sticks. We carefully went through the argument for this being NP-Complete, reducing from SUBSET SUM.