Changes

& ^{\backprime\backprime} \operatorname{,} ^{\prime\prime}

& ^{\backprime\backprime} \operatorname{,} ^{\prime\prime}

& \cdot

& \cdot

& S_k \\

& S_k

\\

\end{array}</math>

\end{array}</math>

|}

|}

When there is no possibility of confusion, the letter <math>^{\backprime\backprime} \operatorname{R} ^{\prime\prime}</math> can be used either as a string variable that ranges over the set of runes or else as a type name for the class of runes.  The latter reading amounts to the enlistment of a fresh intermediate symbol, <math>^{\backprime\backprime} \operatorname{R} ^{\prime\prime} \in \mathfrak{Q},</math> as a part of a new grammar for <math>\mathfrak{C} (\mathfrak{P}).</math>  In effect, <math>^{\backprime\backprime} \operatorname{R} ^{\prime\prime}</math> affords a grammatical recognition for any rune that forms a part of a sentence in <math>\mathfrak{C} (\mathfrak{P}).</math>  In situations where these variant usages are likely to be confused, the types of strings can be indicated by means of expressions like <math>r <: R\!</math> and <math>W <: R.\!</math>

When there is no possibility of confusion, the letter <math>^{\backprime\backprime} \operatorname{R} ^{\prime\prime}</math> can be used either as a string variable that ranges over the set of runes or else as a type name for the class of runes.  The latter reading amounts to the enlistment of a fresh intermediate symbol, <math>^{\backprime\backprime} \operatorname{R} ^{\prime\prime} \in \mathfrak{Q},</math> as a part of a new grammar for <math>\mathfrak{C} (\mathfrak{P}).</math>  In effect, <math>^{\backprime\backprime} \operatorname{R} ^{\prime\prime}</math> affords a grammatical recognition for any rune that forms a part of a sentence in <math>\mathfrak{C} (\mathfrak{P}).</math>  In situations where these variant usages are likely to be confused, the types of strings can be indicated by means of expressions like <math>r <: R\!</math> and <math>W <: R.\!</math>

A ''foil'' is a string of the form <math>^{\backprime\backprime} \, \operatorname{(} \, ^{\prime\prime} \, \cdot \, T \, \cdot \, ^{\backprime\backprime} \, \operatorname{)} \, ^{\prime\prime},</math> where <math>T\!</math> is a tract. Thus, a typical foil <math>F\!</math> has the form:

A "foil" is a string of the form "-(" · T · ")-", where T is a tract.

Thus, a typical foil F has the form:

F  = "-(" · S_1 · "," · ... · "," · S_k · ")-".

{| align="center" cellpadding="8" width="90%"

& ^{\backprime\backprime} \, \operatorname{(} \, ^{\prime\prime}

& S_k

& ^{\backprime\backprime} \, \operatorname{)} \, ^{\prime\prime}

This is just the surcatenation of the sentences S_1, ..., S_k.

This is just the surcatenation of the sentences S_1, ..., S_k.

Given the possibility that this sequence of sentences is empty,

Given the possibility that this sequence of sentences is empty,