Secant line a circle in the Euclidean plane, a line joining two of them would be a 2-secant (or "bisecant") and a line passing through only one of them would be a 1-secant (or "unisecant"). A unisecant in this example need not be a tangent line to the circle. This terminology is often used in incidence geometry and discrete geometry. For instance, the Sylvester–Gallai theorem of incidence geometry states that if points of Euclidean geometry are not collinear then there must exist a 2-secant of them. And the original orchard-planting problem of discrete geometry asks for a bound on the number of
Adventures in a City that does not Exist Adventures in a City that does not Exist Adventures in a City that does not Exist () is a 1974 Soviet children's musical film, directorial debut of Leonid Nechayev. Pioneer Slava Kurochkin dreams of space. He actively studies physics and astronomy, but at the same time he does not read fiction at all. By coincidence, he finds himself in a fairytale town, where the heroes of the most famous books live: "The Snow Queen", "Timur and His Squad", "The White Solitary Sails", "Les Misérables", "Treasure Island" and so on. But, alas, in the city live not only positive characters -