Eigenclass model: Difference between revisions

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=== The embedding ===
 
Any essential structure of &#1013; can be embedded into a set ''<u>V</u>'' that is formed as a cumulative hierarchy over a set of [[urelement|urelements]]s, ''<u>U</u>''.
Elements of ''<u>U</u>'' can be [[Pure set|pure sets]]
that are minimal both in
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:''P<sub style="margin-left:-.8ex">⋆</sub>(X)'' = (''P(X)'' ∖ {∅}) ∪ ''X''
where ''P(X)'' denotes the powerset of ''X''.
The ''ω''-th stage, called ''[[Universe_Universe (mathematics)#In_ordinary_mathematicsIn ordinary mathematics| superstructure]]'' in the field of [[non-standard analysis]],{{efn|
However, we provide a slightly different construction by removing the empty set.
}}
is the union of all previous stages.
This set stands for the inheritance root &ndash; it is therefore denoted ''<u>r</u>''.
The set ''<u>V</u>'' then equals the powerset cumulation of ''<u>r</u>'',
i.e. ''<u>V</u> = P<sub style="margin-left:-.8ex">⋆</sub><sup>ω+1</sup>(<u>U</u>) = P<sub style="margin-left:-.8ex">⋆</sub>(<u>r</u>)''.
 
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The following are satisfied:
<!-- -->
<table border=0{| cellpadding=2 style="margin:1ex 3ex;">
<tr|- valign=top>
<td>| ''x.ec'' = {''x''}</td>
<td>| if ''x'' is terminal
(or ''x'' is from the eigenclass chain of a terminal),</td>
<tr|- valign=top>
</tr>
<td| style="padding-right:2ex;white-space:nowrap;"> | ''x.ec = P(x)'' ∖ {∅}</td>
<tr valign=top>
<td>| if (and only if) ''x'' ∈ ''<u>r</u>'',</td>
<td style="padding-right:2ex;white-space:nowrap;">''x.ec = P(x)'' ∖ {∅}</td>
<tr|- valign=top>
<td>if (and only if) ''x'' ∈ ''<u>r</u>'',</td>
<td>| ''x.ec'' &sub; ''x''</td>
</tr>
<td>| if (and only if) ''x'' &#1013; ''x''.</td>
<tr valign=top>
|}
<td>''x.ec'' &sub; ''x''</td>
<td>if (and only if) ''x'' &#1013; ''x''.</td>
</tr>
</table>
 
Any subset ''<u>O</u>'' of ''<u>V</u>'' such that ''<u>r</u>'' ∈ ''<u>O</u>'' and ''<u>O</u>.ec'' = ''<u>V</u>.ec'' ∩ ''<u>O</u>'' forms an "object system": the substructure