A General Framework for Globally Optimized Pagination

Pagination problems deal with questions around transforming a source text stream into a formatted document by dividing it up into individual columns and pages, including adding auxiliary elements that have some relationship to the source stream data but may allow a certain amount of variation in placement (such as figures or footnotes). Traditionally the pagination problem has been approached by separating it into one of micro-typography (e.g., breaking text into paragraphs, also known as h&j) and one of macro-typography (e.g., taking a galley of already formatted paragraphs and breaking them into columns and pages) without much interaction between the two. While early solutions for both problem spaces used simple greedy algorithms, Knuth and Plass introduced in the '80s a global-fit algorithm for line breaking that optimizes the breaks across the whole paragraph [1]. This algorithm was implemented in TeX'82 [2] and has since kept its crown as the best available solution for this space. However, for macro-typography there has been no (successful) attempt to provide globally optimized page layout: all systems to date (including TeX) use greedy algorithms for pagination. Various problems in this area have been researched (e.g., [3,4,5,6]) and the literature documents some prototype development. But none of these prototypes have been made widely available to the research community or ever made it into a generally usable and publicly available system. This paper presents a framework for a global-fit algorithm for page breaking based on the ideas of Knuth/Plass. It is implemented in such a way that it is directly usable without additional executables with any modern TeX installation. It therefore can serve as a test bed for future experiments and extensions in this space. At the same time a cleaned-up version of the current prototype has the potential to become a production tool for the huge number of TeX users world-wide. The paper also discusses two already implemented extensions that increase the flexibility of the pagination process: the ability to automatically consider existing flexibility in paragraph length (by considering paragraph variations with different numbers of lines [7]) and the concept of running the columns on a double spread a line long or short. It concludes with a discussion of the overall approach, its inherent limitations and directions for future research. [1] D. E. Knuth and M. F. Plass. Breaking Paragraphs into Lines. Software-Practice and Experience, 11(11):1119-1184, Nov. 1981. [2] D. E. Knuth. TeX: The Program, volume B of Computers and Typesetting. Addison-Wesley, Reading, MA, USA, 1986. [3] A. Bruggemann-Klein, R. Klein, and S. Wohlfeil. Computer science in perspective. Chapter On the Pagination of Complex Documents, pages 49-68. Springer-Verlag New York, Inc., New York, NY, USA, 2003. [4] C. Jacobs, W. Li, and D. H. Salesin. Adaptive document layout via manifold content. In Second International Workshop on Web Document Analysis (wda2003), Liverpool, UK, 2003, 2003. [5] A. Holkner. Global multiple objective line breaking. Master's thesis, School of Computer Science and Information Technology, RMIT University, Melbourne, Victoria, Australia, 2006. [6] P. Ciancarini, A. Di Iorio, L. Furini, and F. Vitali. High-quality pagination for publishing. Software-Practice and Experience, 42(6):733-751, June 2012. [7] T. Hassan and A. Hunter. Knuth-Plass revisited: Flexible line-breaking for automatic document layout. In Proceedings of the 2015 ACM Symposium on Document Engineering, DocEng '15, pages 17-20, New York, NY, USA, 2015.