Andrzej Ehrenfeucht (Polish: [ˈand.ʐɛj ˈɛrɛnfɔjxt], born August 8, 1932) is a Polish American mathematician and computer scientist. He formulated the Ehrenfeucht–Fraïssé game, using the back-and-forth method given by Roland Fraïssé in his PhD thesis. The Ehrenfeucht–Mycielski sequence is also named after him. Two journal issues have come out in his honor, one at his 65th birthday in Lecture Notes in Computer Science, and one at his 80th in Theoretical Computer Science.