A seemingly endless variety of food was sprawled over several tables at the home of Judith L. Baxter and her husband, mathematician Stephen D. Smith, in Oak Park, Ill., on a cool Friday evening in September 2011. Canapés, homemade meatballs, cheese plates and grilled shrimp on skewers crowded against pastries, pâtés, olives, salmon with dill sprigs and feta wrapped in eggplant. Dessert choices included—but were not limited to—a lemon mascarpone cake and an African pumpkin cake. The sun set, and champagne flowed, as the 60 guests, about half of them mathematicians, ate and drank and ate some more.