Similarity Problems in Paragraph Justification: An Extension to the Knuth-Plass Algorithm

In high quality typography, consecutive lines beginning or ending with the same word or sequence of characters is considered a defect. We have implemented an extension to TEX'S paragraph justification algorithm which handles this problem. Experimentation shows that getting rid of similarities is both worth addressing and achievable. Our extension automates the detection and avoidance of similarities while leaving the ultimate decision to the professional typographer, thanks to a new adjustable cursor. The extension is simple and lightweight, making it a useful addition to production engines.