Dear Andrei, Speaking about research programmes, Makkai's generalized sketches should definitely be mentioned. An easy introduction can be found in A Diagrammatic Logic for Object-Oriented Visual Modeling Zinovy Diskin and Uwe Wolter DOI Bookmark: 10.1016/j.entcs.2008.10.041 It provides references to Makkai's papers and some other sources, and briefly describes some history and motivations. You may skip all sentiments about engineering applications, or do just the opposite -- pay attention to them -- at least, this is what granting agencies like. There are two distinctions from Makkai's sketches: a signature of diagram predicates is a category rather than a set, and semantics is given in terms of functors into sketches rather than from them. ZD 2009/5/20 Andre.Rodin <Andre.Rodin@ens.fr>:
Dear Charles and others:
this
http://www.cwru.edu/artsci/math/wells/pub/pdf/sketch.pdf
is your very useful overview of Sketch theory dated back to 1993. I wonder how much it omits today: are there significant research programmes in this field emerged during last 15 years? What should I look at first of all? Many thanks in advance.
Andrei