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− | <pre>
| + | Linkages can be chained together to form sequences of indications or <math>n\!</math>-tuples, without worrying too much about the order of collecting terms in the corresponding angle brackets. |
− | 1. Carets linkages can be chained together to form sequences of indications or n tuples, without worrying too much about the order of collecting terms in the corresponding angle brackets.
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− | a^b^c = <a, b, c> = <a, <b, c>> = <<a, b>, c>. | + | {| align="center" cellspacing="8" width="90%" |
| + | | |
| + | <math>\begin{matrix} |
| + | a \widehat{~} b \widehat{~} c |
| + | & = & |
| + | (a, b, c) |
| + | & = & |
| + | (a, (b, c)) |
| + | & = & |
| + | ((a, b), c). |
| + | \end{matrix}</math> |
| + | |} |
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− | These equivalences depend on the existence of natural isomorphisms between different ways of constructing n place product spaces, that is, on the associativity of pairwise products, a not altogether trivial result (MacLane, CatWorkMath, ch. 7). | + | These equivalences depend on the existence of natural isomorphisms between different ways of constructing <math>n\!</math>-place product spaces, that is, on the associativity of pairwise products, a not altogether trivial result (Mac Lane, CatWorkMath, ch. 7). |
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− | 2. Higher order indications (HOIs)?
| + | Higher Order Indications (HOIs)? |
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− | ^x = < , x> x^ = <x, > ?
| + | {| align="center" cellspacing="8" width="90%" |
− | ^^x = < , < , x>> x^^ = <<x, >, > ?
| + | | |
| + | <math>\begin{matrix} |
| + | \widehat{~} x & = & (~, x) & ? |
| + | \\[4pt] |
| + | x \widehat{~} & = & (x, ~) & ? |
| + | \\[4pt] |
| + | \widehat{~}~\widehat{~} x & = & (~, (~, x)) & ? |
| + | \\[4pt] |
| + | x \widehat{~}~\widehat{~} & = & ((x, ~), ~) & ? |
| + | \end{matrix}</math> |
| + | |} |
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| + | <pre> |
| In talking about properties and classes of relations, one would like to refer to "all relations" as forming a topic of potential discussion, and then take it as a background for contemplating ... | | In talking about properties and classes of relations, one would like to refer to "all relations" as forming a topic of potential discussion, and then take it as a background for contemplating ... |
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