History of combinatorics (current) Spring (hydrology) Kidnapped robot problem Propositional logic Distance between two parallel lines Gelman Library Martin Fowler (software engineer) BitTorrent (protocol) Pinyin input method FutureBASIC Bandwidth (signal processing) Fold (higher-order function) No. 1 Wing AAC SWLABR Open letter on artificial intelligence (2015) Gadget (machine instruction sequence) Net zero LinuxTag Plancherel theorem