|Diagrams, Visual Languages, and Spatial Parsing|
Binary trees and bar charts are examples of visual
language conventions which relate spatial arrangement to
underlying tree structure. A spatial parser has been written
which can process these languages (among others). The parser
takes two inputs: a machine
Thus a visual grammar along with a spatial parser is one way of formalizing the conventions for relating spatial arrangement to tree structure in diagrams.
The purpose of spatial parsing is to aid in the processing of visual languages. As an operational definition of visual language, we say: A visual language is a set of spatial arrangements of text-graphic objects with a semantic interpretation that is used in carrying out communicative actions in the world.*
Spatial parsing deals with the spatial
arrangement of the text
Diagrams as Formal Visual Languages
When a person employs text and graphic objects in communication, those objects have meaning under a system of interpretation, or visual language. Formal visual languages are ones which have been explicitly designed to be syntactically and semantically unambiguous. It seems that most diagraming systems would fall under this definition, especially those with published conventions or public agreement on them. A gray area could be called folk diagrams, which in use are unambiguous, but for which there are no explicit conventions.
And the remainder of the artifacts produced by human text
Spatial parsing recovers underlying syntactic structure so that a spatial arrangement of visual objects can be interpreted as a phrase in a particular visual language. Interpretation consists of parsing and then semantic processing so that appropriate action can be taken in response to the visual phrase. Appropriate action may include: assistance for agile manual manipulation of objects, compilation into an internal form representing the semantics, translation into another text-graphic language, or simply execution as an instruction to the computer.
Semantics is discussed in further detail in Spatial Parsing for Visual Languages and Visual Grammars For Visual Languages.
* Note that if we substitute ``strings of textual
symbols'' for ``spatial arrangements of text
** Again the definition is parallel to one for textual parsing:
textual parsing is the (rule
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