YAP3: improved detection of similarities in computer program and other texts. In spite of years of effort, plagiarism in student assignment submissions still causes considerable difficulties for course designers; if students’ work is not their own, how can anyone be certain they have learnt anything? YAP is a system for detecting suspected plagiarism in computer programs and other texts submitted by students. The paper reviews YAP3, the third version of YAP, focusing on its novel underlying algorithm - Running-Karp-Rabin Greedy-String-Tiling (or RKS-GST), whose development arose from the observation with YAP and other systems that students shuffle independent code segments. YAP3 is able to detect transposed subsequences, and is less perturbed by spurious additional statements. The paper concludes with a discussion of recent extension of YAP to English texts, further illustrating the flexibility of the YAP approach.