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→‎Note 22: markup + rewrite
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The two main operators that we have worked with up to this point are the enlargement or shift operator <math>\operatorname{E} : X^\circ \to \operatorname{E}X^\circ</math> and the difference operator <math>\operatorname{D} : X^\circ \to \operatorname{E}X^\circ.</math>
 
The two main operators that we have worked with up to this point are the enlargement or shift operator <math>\operatorname{E} : X^\circ \to \operatorname{E}X^\circ</math> and the difference operator <math>\operatorname{D} : X^\circ \to \operatorname{E}X^\circ.</math>
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<math>\operatorname{E}</math> and <math>\operatorname{D}</math> act on propositions in <math>X^\circ,</math> that is, propositions of the form <math>f : X \to \mathbb{B}</math> that are said to be ''about'' the subject matter of <math>X,\!</math> and they produce extended propositions of the forms <math>\operatorname{E}f, \operatorname{D}f : \operatorname{E}X \to \mathbb{B},</math> propositions whose extended sets of variables allow them to be read as being about specified collections of changes that conceivably occur in <math>X.\!</math>
    
<pre>
 
<pre>
E and D take a proposition in X%, that is, a proposition f : X -> B
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that is said to be "about" the subject matter of X, and produce the
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extended propositions Ef, Df : EX -> B, which may be interpreted as
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being about specified collections of changes that might occur in X.
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Here we have need of visual representations,
 
Here we have need of visual representations,
 
some array of concrete pictures to anchor our
 
some array of concrete pictures to anchor our
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