[Inquiry] Re: Theme One Program

[Jon Awbrey]

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TOP.  Expository Note 5

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3.  Lexical, Literal, Logical

Theme One puts cactus graphs to work in three distinct but related ways,
what we shall call the "lexical", the "literal", and the "logical" uses,
and these applications make use of three distinct but overlapping subsets
of the broader species of cacti.  Thus, we shall find ourselves speaking
of graphs, files, and expressions of lexical, literal, and logical types,
depending on our point of view and on our focus at the moment in question.

The logical class of cacti is the broadest, encompassing the whole species
that was described above, and so we have already seen a typical example of
a logical cactus, in its avatars as an abstract graph, a pointer structure,
and a string of characters suitable for storage in an external text file.

But being a logical cactus is not just a matter of syntactic form --
it means being subject to meaningful interpretations as a sign of
a logical proposition.  From a logical perspective, we expect our
cactus expressions to 'express' something, a proposition that can
be true or false of something.

Still, before we can get to this logical, interpretive, semantic aspect
of cactus graphs we have a bit more to do in the way of detailing their
syntactic utilities.  So those are the matters that I will turn to next.

Jon Awbrey

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