Any five points in the plane contain a convex quadrilateral according to this person’s so-called “happy ending problem.” The Green-Tao theorem proves a specific case of a conjecture named after this person, which states that any substantial set has arbitrarily long arithmetic progressions. This person is the alphabetically first namesake of a model used to generate random graphs given a fixed (-5[1])number of nodes and edges. Along with George (*) Szekeres (“SEK-eh-resh”), this man proved the first upper bound for Ramsey numbers. This man popularized a technique which proves the existence of objects by showing the chance of choosing them randomly is nonzero called the probabilistic method. For 10 points, name this eccentric Hungarian mathematician (10[1])whose (10[1])namesake “number” quantifies distance from him via coauthorship of papers. ■END■ (10[1])