A short story in Isaac Asimov's series of robot stories about Elijah Baley and Daneel Olivaw. In "Mirror Image", Elijah must solve a problem concerning two mathematicians. Each mathematician has accused the other one of stealing his important idea. The mathematicians are Spacers and will not submit to being interrogated by an Earthman. Elijah has to find out who is guilty by interviewing their robot servants, although robots will lie if ordered to do so or to protect humans from harm.