z3: sat
verified: n=15, edges=30, min degree=4, contains C4=False
edges: [(0, 1), (0, 2), (0, 7), (0, 8), (1, 3), (1, 8), (1, 14), (2, 5), (2, 7), (2, 12), (3, 10), (3, 11), (3, 14), (4, 6), (4, 7), (4, 9), (4, 14), (5, 9), (5, 10), (5, 12), (6, 7), (6, 11), (6, 13), (8, 9), (8, 13), (9, 10), (10, 11), (11, 13), (12, 13), (12, 14)]