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:* A bare terminal edge, symbolized by a vertical bar <math>\vert</math> in text, is known as a ''stick''.

:* A bare terminal edge, symbolized by a vertical bar <math>\vert</math> in text, is known as a ''stick''.

Let the ''replacement expression'' of the form ''Q''[o/''x''] denote the proposition that results from ''Q'' by replacing every token of the variable ''x'' with a blank, that is to say, by erasing ''x''.

Let the ''replacement expression'' of the form <math>Q[\circ /x]</math> denote the proposition that results from <math>Q\!</math> by replacing every token of the variable <math>x\!</math> with a blank, that is to say, by erasing <math>x.\!</math>

Let the ''replacement expression'' of the form ''Q''[|/''x''] denote the proposition that results from ''Q'' by replacing every token of the variable ''x'' with a stick stemming from the site of ''x''.

Let the ''replacement expression'' of the form <math>Q[\,\vert /x]</math>  denote the proposition that results from <math>Q\!</math> by replacing every token of the variable <math>x\!</math> with a stick stemming from the site of <math>x.\!</math>

In the case of a proposition ''Q'', that is, an expression of it, not having a token of the designated variable ''x'', let it be stipulated that ''Q''[o/''x''] = ''Q'' = ''Q''[|/''x''].

In the case of a propositional expression <math>Q\!</math> that has no token of the designated variable <math>x,\!</math> let it be stipulated that <math>Q[\circ /x] = Q = Q[\,\vert /x].</math>

I think that I am at long last ready to state the following:

I think that I am at long last ready to state the following: