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Definition df-ndx 14117
Description: Define the structure component index extractor. See theorem ndxarg 14134 to understand its purpose. The restriction to allows to exist as a set, since is a proper class. In principle, we could have chosen or (if we revise all structure component definitions such as df-base 14119) another set such as the natural ordinal numbers (df-om 6447). (Contributed by NM, 4-Sep-2011.)
Assertion
Ref Expression
df-ndx

Detailed syntax breakdown of Definition df-ndx
StepHypRef Expression
1 cnx 14111 . 2
2 cid 4602 . . 3
3 cn 10268 . . 3
42, 3cres 4813 . 2
51, 4wceq 1687 1
Colors of variables: wff setvar class
This definition is referenced by:  wunndx  14130  ndxarg  14134
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