On the Syntax of Diagrams *    

Fred Lakin, the paul graphic charlie company

I find it useful to defer making the syntactic distinction between text and graphics for as long as possible. So I ambiguously refer to a discernible visual chunk      like a diagram      as a "text graphic object", which may in turn recursively be a pattern of other text graphic objects. At the bottom finally are visual "drawlines".

A text-graphic object is either a line or a pattern:

A line is a either a drawline or a textline

A drawline is either a colored stroke drawn through one or more locations,
or a (not necessarily rectangular) group of colored dots:

A textline is one or more characters (a character is a pattern of one or more drawlines)

A pattern is a group of one or more text-graphic objects

Details and Examples

Text graphic object notation: how the spider webs work, various relations of spatial structure to tree structure.

And, no, text graphic object notation is not the syntax for diagrams, but rather a notation for describing various possible syntaxes ... at the bottom is an operational definition of structure in text graphic images.

Romanji text: example syntax showing how Roman style text can be defined as 26 little patterns with certain conventions for arranging them spatially.

Diagrams, visual languages, and spatial parsing: some definitions.

Binary Trees: example syntax; and machine readable, visually notated context free grammar used by a spatial parser to recover underlying syntactic structure.

Bar charts: example syntax; visual grammar.

Blackboard Image with embedded diagrams: example syntax only (grammar and parsing part of on going work ...)

Textual BNF: character only syntax for text graphic objects and Romanji text


* Originally written for Alan Blackwell's THINKING WITH DIAGRAMS '97 WORKSHOP, Portsmouth, England, January 9-10, 1997; subsequently modified after reading Yuri Engelhardt's thesis July 25, 2002. A one Web page summary of this article appeared at Alan's site, and a paper version was printed in the proceedings.

© 1996, 2002 PGC