If the category of people e-quainted with Arwen contains three people and
if these three are mutually e-stranged, we are finished. Otherwise, some two of
them are e-quainted and these two, together with Arwen, are mutually e-quainted.
Let's model the situation using graphs. Begin by identifying some group of
six guests with the vertices of Kf,. If guests i and j are e-quainted, color edge
V¡VJ black; if they are not, color it white. From this perspective, our observation
is that the resulting figure contains a black triangle or a white triangle.
There is another way to look at this model. Let G be a graph on six vertices.
Visualize G as a spanning subgraph of some fixed illustration of Kf,. Then "white
out" the edges that do not belong to G. This process leads to a natural one-toone
correspondence between the different black-white edge colorings of Kf, and
the different graphs on 6 vertices. In this correspondence a black triangle in the
edge coloring represents a clique in the corresponding graph, and a white triangle
represents an independent set. Evidently, a)(G) > 3 or ot(G) > 3, for every graph