ONT Re: Sequential Interactions Generating Hypotheses
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SIGH. Note 8
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Two-Level Formal Languages (2-FL's)
A "k-level formal language" (k-FL) is
a selected set of finite sequences of
a selected set of finite sequences of ...
the finite set of symbols, called the
"alphabet", that is provided to start,
where the selection of sequences from
the previous level is enacted k times.
In particular, let L be a "2-level formal language" (2-FL)
over an alphabet !A!. Then L is composed of a first level
language L_1 c !A!* and a second level language L_2 c L_1*,
where the "kleene-star" of a set X, written X*, is the set
of all finite sequences over X. It is generally convenient
to let the name L denote the whole structure L = <L_1, L_2>.
It's an arbitrary matter what we call the levels of a 2-FL.
Depending on what seems natural in a particular discussion,
we may refer to L_1 and L_2 as "strings" and "strands", as
"words" and "sentences", as "phrases" and "clauses", or as
"sentences" and "paragraphs", respectively, just to name
a few of the possible options that come right to mind.
Jon Awbrey
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